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  • Column liquid chromatography  (1,216)
  • Chemistry
  • Springer  (1,251)
  • Islamic Azad University, Science and Research Branch, Tehran, Fisheries  (13)
  • NOAA/National Centers for Coastal Ocean Science  (10)
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  • 1
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    NOAA/National Centers for Coastal Ocean Science | Silver Spring, MD
    In:  http://aquaticcommons.org/id/eprint/14678 | 403 | 2014-02-24 20:59:15 | 14678 | United States National Ocean Service
    Publication Date: 2021-07-01
    Description: This report is the second in a series from a project to assess land-based sources of pollution (LBSP) and effects in the St. Thomas East End Reserves (STEER) in St. Thomas, USVI, and is the result of a collaborative effort between NOAA’s National Centers for Coastal Ocean Science, the USVI Department of Planning and Natural Resources, the University of the Virgin Islands, and The Nature Conservancy.Passive water samplers (POCIS) were deployed in the STEER in February 2012. Developed by the US Geological Survey(USGS) as a tool to detect the presence of water solublecontaminants in the environment, POCIS samplers were deployed in the STEER at five locations. In addition to the February 2012 deployment, the results from an earlier POCIS deployment in May 2010 in Turpentine Gut, a perennial freshwater stream which drains to the STEER, are also reported.A total of 26 stormwater contaminants were detected at least once during the February 2012 deployment in the STEER. Detections were high enough to estimate ambient water concentrations for nine contaminants using USGS sampling rate values. From the May 2010 deployment in Turpentine Gut, 31 stormwater contaminants were detected, and ambient water concentrations could be estimated for 17 compounds.Ambient water concentrations were estimated for a numberof contaminants including the detergent/surfactant metabolite 4-tert-octylphenol, phthalate ester plasticizers DEHP and DEP, bromoform, personal care products including menthol, indole, n,n-diethyltoluamide (DEET), along with the animal/plant sterol cholesterol, and the plant sterol beta-sitosterol. Only DEHP appeared to have exceeded a water quality guideline for the protection of aquatic organisms.
    Keywords: Chemistry ; Environment ; Pollution
    Repository Name: AquaDocs
    Type: monograph
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  • 2
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    NOAA/National Centers for Coastal Ocean Science | Silver Spring, MD
    In:  http://aquaticcommons.org/id/eprint/14679 | 403 | 2014-02-24 19:16:48 | 14679 | United States National Ocean Service
    Publication Date: 2021-07-01
    Description: This report contains a chemical and biological characterization of sediments from the St. Thomas East End Reserves (STEER) in St. Thomas, U.S. Virgin Islands (USVI). The STEER Management Plan (published in 2011) identified chemical contaminants and habitat loss as high or very high threats and called for a characterization of chemical contaminants as well as an assessment of their effects on natural resources. The baseline information contained in this report on chemical contaminants, toxicity and benthic infaunal community composition can be used to assess current conditions, as well as the efficacy of future restoration activities. In this phase of the project, 185 chemical contaminants, including a number of organic (e.g., hydrocarbons and pesticides) and inorganic (e.g., metals) compounds, were analyzed from 24 sites in the STEER. Sediments were also analyzed using a series of toxicity bioassays, including amphipod mortality, sea urchin fertilization impairment, and the cytochrome P450 Human Reporter Gene System (HRGS), along with a characterization of the benthic infaunal community. Higher levels of chemical contaminants were found in Mangrove Lagoon and Benner Bay in the western portion of the study area than in the eastern area. The concentrations of polychlorinated biphenyls (PCBs), DDT (dichlorodiphenyltrichloroethane), chlordane, zinc, copper, lead and mercury were above a NOAA sediment quality guideline at one or more sites, indicating impacts may be present in more sensitive species or life stages in the benthic environment. Copper at one site in Benner Bay, however, was above a NOAA guideline indicating that effects on benthic organisms were likely. The antifoulant boat hull ingredient tributyltin, or TBT, was found at the third highest concentration in the history of NOAA’s National Status and Trends (NS&T) Program, which monitors the Nation’s coastal and estuarine waters for chemical contaminants and bioeffects. Unfortunately, there do not appear to be any established sediment quality guidelines for TBT. Results of the bioassays indicated significant sediment toxicity in Mangrove Lagoon and Benner Bay using multiple tests. The benthic infaunal communities in Mangrove Lagoon and Benner Bay appeared severely diminished.
    Keywords: Chemistry ; Environment ; Pollution
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  • 3
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    NOAA/National Centers for Coastal Ocean Science | Charleston, SC
    In:  http://aquaticcommons.org/id/eprint/14710 | 403 | 2014-02-22 22:53:38 | 14710 | United States National Ocean Service
    Publication Date: 2021-07-02
    Description: Porphyrin metabolic disruption from exposure to xenobiotic contaminants such as heavy metals, dioxins, and aromatic hydrocarbons can elicit overproduction of porphyrins. Measurement of porphyrin levels, when used in conjunction with other diagnostic assays, can help elucidate an organism’s physiological condition and provide evidence for exposure to certain toxicants. A sensitive microplate fluorometric assay has been optimized for detectingtotal porphyrin levels in detergent solubilized protein extracts from symbiotic, dinoflagellate containing cnidarian tissues. The denaturing buffer used in this modified assay contains a number of potentially interfering components (e.g., sodium dodecyl sulfate (SDS), dithiothreitol (DTT), protease inhibitors, and chlorophyll from the symbiotic zooxanthellae), which required examination and validation. Examination of buffer components were validated for use in this porphyrin assay; while the use of a specific spectrofluorometric filter (excitation 400 ± 15 nm; emission 600 ± 20 nm) minimized chlorophyll interference. The detection limit for this assay is 10 fmol of total porphyrin per μg of total soluble protein and linearity is maintained up to 5000 fmol. The ability to measure total porphyrins in a SDS protein extract now allows a single extract to be used in multiple assays. This is an advantage over classical methods, particularly when tissue samples are limiting, as is often the case with coral due to availability and collection permit restrictions.
    Description: NOAA Technical Memorandum CRCP 17
    Keywords: Biology ; Chemistry ; Fisheries
    Repository Name: AquaDocs
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  • 4
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    NOAA/National Centers for Coastal Ocean Science | Charleston, SC
    In:  http://aquaticcommons.org/id/eprint/14759 | 403 | 2014-02-26 21:18:00 | 14759 | United States National Ocean Service
    Publication Date: 2021-07-03
    Description: The mucus surface layer of corals plays a number of integral roles in their overall health and fitness. This mucopolysaccharide coating serves as vehicle to capture food, a protective barrier against physical invasions and trauma, and serves as a medium to host a community of microorganisms distinct from the surrounding seawater. In healthy corals the associated microbial communities are known to provide antibiotics that contribute to the coral’s innate immunity and function metabolic activities such as biogeochemical cycling.Culture-dependent (Ducklow and Mitchell, 1979; Ritchie, 2006) and culture-independent methods (Rohwer, et al., 2001; Rohwer et al., 2002; Sekar et al., 2006; Hansson et al., 2009; Kellogg et al., 2009) have shown that coral mucus-associated microbial communities can change with changes in the environment and health condition of the coral. These changes may suggest that changes in the microbial associates not only reflect health status but also may assist corals in acclimating to changing environmental conditions. With the increasing availability of molecular biology tools, culture-independent methods are being used more frequently for evaluating the health of the animal host. Although culture-independent methods are able to provide more in-depth insights into the constituents of the coral surface mucus layer’s microbial community, their reliability and reproducibility rely on the initial sample collection maintaining sample integrity. In general, a sample of mucus is collected from a coral colony, either by sterile syringe or swab method (Woodley, et al., 2008), and immediately placed in a cryovial. In the case of a syringe sample, the mucus is decanted into the cryovial and the sealed tube is immediately flash-frozen in a liquid nitrogen vapor shipper (a.k.a., dry shipper). Swabs with mucus are placed in a cryovial, and the end of the swab is broken off before sealing and placing the vial in the dry shipper. The samples are then sent to a laboratory for analysis. After the initial collection and preservation of the sample, the duration of the sample voyage to a recipient laboratory is often another critical part of the sampling process, as unanticipated delays may exceed the length of time a dry shipper can remain cold, or mishandling of the shipper can cause it to exhaust prematurely. In remote areas, service by international shipping companies may be non-existent, which requires the use of an alternative preservation medium. Other methods for preserving environmental samples for microbial DNA analysis include drying on various matrices (DNA cards, swabs), or placing samples in liquid preservatives (e.g., chloroform/phenol/isoamyl alcohol, TRIzol reagent, ethanol). These methodologies eliminate the need for cold storage, however, they add expense and permitting requirements for hazardous liquid components, and the retrieval of intact microbial DNA often can be inconsistent (Dawson, et al., 1998; Rissanen et al., 2010).A method to preserve coral mucus samples without cold storage or use of hazardous solvents, while maintaining microbial DNA integrity, would be an invaluable tool for coral biologists, especially those in remote areas. Saline-saturated dimethylsulfoxide-ethylenediaminetetraacetic acid (20% DMSO-0.25M EDTA, pH 8.0), or SSDE, is a solution that has been reported to be a means of storing tissue of marine invertebrates at ambient temperatures without significant loss of nucleic acid integrity (Dawson et al., 1998, Concepcion et al., 2007). While this methodology would be a facile and inexpensive way to transport coral tissue samples, it is unclear whether the coral microbiota DNA would be adversely affected by this storage medium either by degradation of the DNA, or a bias in the DNA recovered during the extraction process created by variations in extraction efficiencies among the various community members. Tests to determine the efficacy of SSDE as an ambient temperature storage medium for coral mucus samples are presented here.
    Keywords: Chemistry ; Fisheries
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  • 5
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    NOAA/National Centers for Coastal Ocean Science | Silver Spring, MD
    In:  http://aquaticcommons.org/id/eprint/14868 | 403 | 2014-03-06 18:57:33 | 14868 | United States National Ocean Service
    Publication Date: 2021-06-27
    Description: This report presents an initial characterization of chemical contamination in coral tissues (Porites astreoides) from southwest Puerto Rico. It is the second technical report from a project to characterize chemical contaminants and assess linkages between contamination and coral condition. The first report quantified chemical contaminants in sediments from southwest Puerto Rico. This document summarizes the analysis of nearly 150 chemical contaminants in coral tissues. Although only eight coral samples were collected, some observations can be made on the correlations between observed tissue and sediment contaminant concentrations. The concentrations of polycyclic aromatic hydrocarbons (PAHs), typically associated with petroleum spills and the combustion of fossil fuels, and polychlorinated biphenyls (PCBs) in the coral tissues were comparable to concentrations found in adjacent sediments. However, the concentration of a chemical contaminant (e.g., PAHs) in the coral tissues at a particular site was not a good predictor of what was in the adjacent sediments. In addition, the types of PAHs found in the coral tissues were somewhat different (higher ratios of alkylated PAHs) than in sediments. The levels of PCBs and DDT in coral tissues appeared higher just outside of Guanica Bay, and there was evidence of a downstream concentration gradient for these two contaminant classes. The trace elements copper, zinc and nickel were frequently detected in coral tissues, and the concentration in the corals was usually comparable to that found in adjacent sediments. Chromium was an exception in that it was not detected in any of the coral tissues analyzed. Additional work is needed to assess how spatial patterns in chemical contamination affect coral condition, abundance and distribution.
    Description: National Status and Trends Program for Marine Environmental Quality
    Keywords: Chemistry ; Management ; Pollution
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  • 6
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    NOAA/National Centers for Coastal Ocean Science | Charleston, SC
    In:  http://aquaticcommons.org/id/eprint/14864 | 403 | 2014-03-06 18:36:18 | 14864 | United States National Ocean Service
    Publication Date: 2021-06-27
    Description: Models that help predict fecal coliform bacteria (FCB) levels in environmental waters can be important tools for resource managers. In this study, we used animal activity along with antibiotic resistance analysis (ARA), land cover, and other variables to build models that predict bacteria levels in coastal ponds that discharge into an estuary. Photographic wildlife monitoring was used to estimate terrestrial and aquatic wildlife activity prior to sampling. Increased duck activity was an important predictor of increased FCB in coastal ponds. Terrestrial animals like deer and raccoon, although abundant, were not significant in our model. Various land cover types, rainfall, tide, solar irradiation, air temperature, and season parameters, in combination with duck activity, were significant predictors of increased FCB. It appears that tidal ponds allow for settling of bacteria under most conditions. We propose that these models can be used to test different development styles and wildlife management techniques to reduce bacterial loading into downstream shellfish harvesting and contact recreation areas.
    Keywords: Chemistry ; Ecology ; Management ; Pollution
    Repository Name: AquaDocs
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  • 7
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    NOAA/National Centers for Coastal Ocean Science | Oxford, MD
    In:  http://aquaticcommons.org/id/eprint/14949 | 403 | 2014-03-14 22:55:57 | 14949 | United States National Ocean Service
    Publication Date: 2021-06-29
    Description: Investigators at the Cooperative Oxford Laboratory (COL) diagnose and study crustaceans, mollusks, finfish, and a variety of other marine and estuarine invertebrates to assess animal health. This edition updates the Histological Techniques for Marine Bivalve Mollusks manual by Howard and Smith (1983) with additional chapters on molluscan and crustacean techniques. The new edition is intended to serve as a guide for histological processing of shellfish, principally bivalve mollusks and crustaceans. Basically, the techniques included are applicable for histopathological preparation of all marine animals, recognizing however that initial necropsy is unique to each species. Photographs and illustrations are provided for instruction on necropsy of different species to simplify the processing of tissues. Several of the procedures described are adaptations developed by the COL staff. They represent techniques based on principles establishedfor the histopathologic study of mammalian and other vertebrate tissues, but modified for marine and aquatic invertebrates. Although the manual attempts to provide adequate information on techniques, it is also intended to serve as a useful reference source to those interested in the pathology of marine animals. General references and recommended reading listed in the back of the manual will provide histological information on species not addressed in the text.
    Description: This edition updates the Histological Techniques for Marine Bivalve Mollusks manual by Howard and Smith (1983) with additional chapters on molluscan and crustacean techniques.
    Keywords: Chemistry ; Fisheries
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  • 8
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    NOAA/National Centers for Coastal Ocean Science | Silver Spring, MD
    In:  http://aquaticcommons.org/id/eprint/14947 | 403 | 2014-03-14 23:06:34 | 14947 | United States National Ocean Service
    Publication Date: 2021-06-29
    Description: This chapter describes the procedures for determining the reproductive stage of oysters, mytilid mussels, and dreissenid mussels collected for NOAA’s National Status and Trends Mussel Watch Project. Analyses are conducted on paraffin-embedded tissues sectioned at a 5-μm thickness and stained using a pentachrome staining procedure. Each slide is examined microscopically to determine the animal’s sex and stage of gonadal development. A semi-quantitative ranking is assigned.
    Keywords: Chemistry ; Fisheries ; Pollution
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  • 9
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    Islamic Azad University, Science and Research Branch, Tehran, Fisheries
    In:  http://aquaticcommons.org/id/eprint/19475 | 17408 | 2016-01-25 09:48:26 | 19475 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-06-29
    Description: Fish sauce is a popular fermented product used in south Asian countries which is made from different small fishes in this research work it was attempted to produce fish sauce from kilka of the Caspian sea, the fish sauce was made from three models of kilka ,such as whole kilka , cooked whole kilka and dressed kilka , each of these models treated it four different fashions of fermentation such as:1- Traditional method, 2- Enzymatic method 3- Microbial method, 4- Mixture of enzyme and microb The results of this investigation showed that time of fermentation for the traditional method was six month, enzymatic method one month, microbial method 3 month and the mixture of enzyme and microb 1 month. The rate of fermentation was least for dressed Kilka, microbial and biochemical changes of Kilka fish sauce were evaluated, total bacterial count was 2.1-6.15 log cfu/ml total volatile nitrogen (TVN) in samples recorded was 250 mg /100g, the amount of protein varied between 10-13 percent, the name of commercial enzymes added was Protamex and Flavourzyme, the bacteria added was L act ob acillus and Pediococous, fish sauce containers fish and 20% salt, temperature of keeping for fermentation was 37 degree c for 6 month.
    Description: PhD
    Description: Advisors: S. Moini Counsellors: A. keyvan, Gh. Vosoughi
    Keywords: Aquaculture ; Chemistry ; Fisheries
    Repository Name: AquaDocs
    Type: thesis
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  • 10
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    Islamic Azad University, Science and Research Branch, Tehran, Fisheries
    In:  http://aquaticcommons.org/id/eprint/19311 | 17408 | 2016-02-08 10:25:26 | 19311 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-06-25
    Description: The first aim of this research was to identify fatty acids, amino acids composition of Thunnustonggol roe and their changes during cold storage (-18'C). The second aim was to determinethe changes of moisture, protein, fat and ash contents of the roe during one year cold storage(-18'C). 60 samples of longtail tuna (Thunnus tonggol) ovaries were randomly collected formBandar-e-Abbas landings. The samples were frozen at-30'C and kept in cold store at -18'Cfor one year. According to a time table, the samples were examined for identification offatty acids, amino acids, moisture, protein, fat, ash, peroxide and T.V.N. and their changeswere evaluated during this time. The results showed that 26 fatty acids were identified. Theunsaturated fatty acids (UFA) and saturated fatty acids (SFA) were 62.33 and 37.6%,respectively, in fresh roe. So that, DHA (C22:6) and oleic acid (C18:1) had high amounts(24.79 and 21.88%) among the UFA and palmitic acid (C16:0) was the most content(22.75%) among the SFA. The PUFA/SFA was 0.91. Also, 17 amino acids were identifiedthat essential amino acids (EAA) and nonessential amino acids (NE) were 10478 and 7562mg/100g, respectively, and E/NE was 1.38. Among the EAA and NE, lysine (2110mg/100g)and aspartic acid (1924 mg/100g) were the most contents. Also, results showed that moisture,ash, protein and fat contents were 72.74, 1.8, 19.88 and 4.53%, respectively, in fresh roe. Theeffects of freezing and cold storage on the roes showed that UFA and SFA contents havereached to 49.83 and 48.07%, respectively, at the end of cold storage. It indicated that thesecompounds change to each other during frozen storage. Also, n-3 and n-6 series of fattyacids were 32.75 and 1.61% in fresh roe. But their contents decreased to 22.96 and 1.25% atthe end of period. Among the fatty acids, 22:6 and C16:0 had the most changes. The changesof fatty acids were significantly at 95% level except for C15:1, C18:3(n-3) and C20:4(n-6).All of the amino acids decreased in frozen storage and their changes were significantly(P〈0.05). EAA was 7818 mg/100g and E/NE was 1.27 at the end of storage period. Amongthe amino acids, leucine and lysine had the most changes. Moisture, ash, protein and fatcontents were 70.13, 1.82, 19.4 and 6.51%, respectively, at the end of storage period. Theperoxide value and T.V.N. increased during storage. So that, their contents have reached to5.86 mg/kg and 26.37 mg/100 g, respectively, at the end of frozen storage. The best shelf lifeof Thunnus tonggol roe was 6 or 7 months, because of lipid oxidation and increasing ofperoxide.
    Description: PhD
    Description: Advisors: S. Moeini Counsellors: A. Keyvan, M. Yousefian
    Keywords: Biology ; Chemistry ; Fisheries
    Repository Name: AquaDocs
    Type: thesis
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  • 11
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    Islamic Azad University, Science and Research Branch, Tehran, Fisheries
    In:  http://aquaticcommons.org/id/eprint/19301 | 17408 | 2016-02-01 21:14:27 | 19301 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-07-14
    Description: Fish protein concentrate (FPC) is a healthy, sustainable and high nutritiveproduct which sanitized produced from fishes in which, protein and othernutrients are more concentrated than in fresh fishes.The aim of this research is to study on the sustainability of FPC producedfrom Kilka (Clupeonella engrauliformis , C. grimmi and C. cultriventris)in two Vaccum Packaging and Modified Atmosphere Packaging atdifferent environmental factors during six months.In our study the analysis of FPC protein showed 91.2%, lipid: 0.5%, ash:3.6%, moisture: 2.3%, Total Volatile Nitrogen: 10 ml/100gr andperoxide: 5meq/kg. Amino acids and fatty acids were also determined.Bacteria and Fungi were lower than 1000 colony. Samples are kept indifferent condition of temperature (5, 20 and 35 degree centigrade),humidity (25, 40 and 90 percent) and light and dark environment in sixmonth.Lipid rate in FPC after 6 months in VP and MAP (60% C02, 30 % N2 and10% O2), packages was decreased but was not significant (P〉0.05). It wasalso detected that increase temperature lead to more decrease in lipidcontent. Protein rate of FPC was decreased from 91.2% to 73.6% duringsix months at 35°C in VP Package and from 91.2% to 69.4% in MAPpackage. These changes were significant (P〈0.05). TVN and PV rate inFPC after 6 months in VP and MAP packages was increased but wassignificant (P〈0.05). Amino acids and fatty acids were also determined.But more changes in MAP packages was detected.
    Description: PhD
    Description: Advisors: Abbas Ali Motalebi Counsellors: Wadud Rzvylar, Aliasghar Khanipoor. The full text document is in Farsi only so it has not been possible for AC Editors to check the metadata input.
    Keywords: Chemistry ; Fisheries
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  • 12
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    Islamic Azad University, Science and Research Branch, Tehran, Fisheries
    In:  http://aquaticcommons.org/id/eprint/19474 | 17408 | 2016-01-25 09:45:47 | 19474 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-06-29
    Description: At the fishing season, in 2000, samples of species persian sturgeon (A. persicus), Severjuga (A. stellatus) and Mullet (L. aurata), were caught from the southern coasts of Caspian Sea and were freezes and preserved in the cold storage for one year They have also become biometery. The tissue's fillet were identified in order to determined the Fatty Acids. This was done during one year, frequently, fresh, two weeks after freezing and then monthly, respectively. So, after the extraction of lipids from the tissues and methylation, was injected to the gas-liquid Chromatography. After calibration, identified Fatty Acids were compared with standards according to their Retention Times. Peroxid value, lipid content and humidity were controlled. The unsaturated Fatty acids had The most amount, and a plenty of Polyunsaturated Fatty acids (PUFA) were observed, so that linoleic (C18:2), a-linolenic (C18:3), Arashidonic (C20:4), EPA (C20:5) and DHA (C22:6) Fatty acids had high amounts. The w-3, PUFA were more in comparison with w-6. The effects of freezing and cold storing on the fish fatty acids , were evaluated by the statistical tests , like SPSS, Tukey, Homogenous and Anova, and showed that in some species, a group of Fatty acids, specially PUFA, had some variation. The peroxide value that indicates the lipid deterioration, increased during toring. So, the best term if preserving in the cold storage, were determined and their Nutrition value and Medical applications due to their consumption were investigated.
    Description: PhD
    Description: Advisors: Sohrab Moeini Counsellors: Amin Keyvan, Mehdi Yousefian
    Keywords: Chemistry ; Fisheries
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    Type: thesis
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  • 13
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    NOAA/National Centers for Coastal Ocean Science | Silver Spring, MD
    In:  http://aquaticcommons.org/id/eprint/2232 | 403 | 2014-02-21 01:55:57 | 2232 | United States National Ocean Service
    Publication Date: 2021-07-12
    Description: Executive Summary:Information found in this report covers the years 1986 through 2005. Mussel Watch began monitoring a suite of trace metals and organic contaminants such as DDT, PCBs and PAHs. Through time additional chemicals were added, and today approximately 140 analytes are monitored. The Mussel Watch Program is the longest running estuarine and coastal pollutant monitoring effort conducted in the United States that is national in scope each year. Hundreds of scientific journal articles and technical reports based on Mussel Watch data have been written; however, this report is the first that presents local, regional and national findingsacross all years in a Quick Reference format, suitable for use by policy makers, scientists, resource managers and the general public.Pollution often starts at the local scale where high concentrations point to a specific source of contamination, yet some contaminants such as PCBs are atmospherically transported across regional and national scales, resulting in contamination far from their origin. Findings presented here showed few national trends for trace metals and decreasing trends for most organic contaminants; however, a wide variety of trends, both increasing and decreasing, emerge at regional and local levels. For most organic contaminants, trends have resulted from state andfederal regulation. The highest concentrations for both metal and organic contaminants are found near urban and industrial areas.In addition to monitoring throughout the nation’s coastal shores and Great Lakes, Mussel Watch samples are stored in a specimen bank so that trends can be determined retrospectively for new and emerging contaminants ofconcern. For example, there is heightened awareness of a group of flame retardants that are finding their way into the marine environment. These compounds, known as polybrominated diphenyl ethers (PBDEs), are now being studied using historic samples from the specimen bank and current samples to determine their spatial distribution. We will continue to use this kind of investigation to assess new contaminant threats.We hope you find this document to be valuable, and thatyou continue to look towards the Mussel Watch Programfor information on the condition of your coastal waters. (PDF contains 118 pages)
    Description: Center for Coastal Monitoring and Assessment
    Keywords: Ecology ; Pollution ; Environment ; Chemistry
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  • 14
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    NOAA/National Centers for Coastal Ocean Science | Silver Spring, MD
    In:  http://aquaticcommons.org/id/eprint/2156 | 403 | 2014-02-21 20:21:25 | 2156 | United States National Ocean Service
    Publication Date: 2021-07-12
    Description: This report summarizes the results of a characterizationof chemical contaminants in the sediments in southwestPuerto Rico. The report is part of a project to integratevarious analytical specialties to assess linkages betweenchemical contaminants and the condition of coral reefs. In this phase of the project, over 120 chemical contaminants were analyzed in sediments collected, including a number of organic (e.g., hydrocarbons), inorganic (e.g., metals), and biological (bacterial) compounds/analytes. The report also provides a preliminary analysis of the association betweensediment contaminants and coral species richness.Overall, the levels of chemical contaminants in the study area between Guanica Bay and the town of La Parguera were fairly low. At most of the sites sampled, particularlyadjacent to the town of La Parguera, concentrations oforganic and inorganic contaminants were below the median values from NOAA’s National Status and Trends Program, which monitors the Nation’s coastal and estuarine waters for chemical contaminants. Elevated levels of a number of contaminant classes were seen at the two sites sampled within Guanica Bay.An initial analysis of modeled PAH (hydrocarbon) data and coral species richness (reef building species) indicated a strong negative correlation between the presence of PAHs in the sediments and coral species richness. Additional work is needed to assess possible reasons for this observed pattern. (PDF contains 126 pages).
    Description: Center for Coastal Monitoring and Assessment
    Keywords: Ecology ; Management ; Environment ; Chemistry
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  • 15
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    Islamic Azad University, Science and Research Branch, Tehran, Fisheries
    In:  http://aquaticcommons.org/id/eprint/19139 | 17408 | 2016-02-06 09:39:39 | 19139 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-07-13
    Description: Biodegradable protein-based film was developed by incorporating cinnamon essential oil(CEO) into whey protein concentrate (WPC) at level of 0.8% and 1.5% v/v. Then physicaland mechanical properties of the films were evaluated. Adding CEO to the WPC matrixdecreased the water vapour permeability of the films and water solubility. Films containingCEO showed significant antibacterial activity both gram-positive and gram-negative strainsand exhibited significant inhibitory effect on the studied fungi. In continue, the effect ofwhey coating and whey coating incorporated with 1.5% CEO on quality and shelf life ofHuso huso fillet during refregrated (4±1°C) storage period were also investigated. The controland treated fish samples were analyzed for microbiological (total viable count, psychrophiliccounts), chemical (PV, TBA, FFA, pH, TVB-N), and sensory characteristics in 4-dayintervals up of microbial, chmical and sensoy analyses indicated lower levels of PV, TBA,FFA, pH, TVB-N in coasted sampels and specially, those with CEO while were kept inrefrigerator. Based on results, whey protein edible coating contain 1.5% cinnamon essentialoil could enhance preserving ability Huso huso during storage cold.
    Description: PhD
    Description: Advisors: M. Rezaei Counsellors: M. Soltioni, A. kamali
    Keywords: Chemistry ; Fisheries
    Repository Name: AquaDocs
    Type: thesis
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  • 16
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    Islamic Azad University, Science and Research Branch, Tehran, Fisheries
    In:  http://aquaticcommons.org/id/eprint/19143 | 17408 | 2016-02-06 09:45:48 | 19143 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-07-13
    Description: The ever-increasing population of the world and the growing need for animal protein has doubled the modern man’s demand for food. Additionally, the improvement in the general public health, and the worsening of environmental/ecological pollution have prompted today’s world to look for ways to procure healthy food. And one such attempt is the use of natural preservatives to decrease the bacterial load in foodstuffs, in other words, to increase their durability.This study evaluates the effects of different concentrations of Zataria multiflora Bioss (EO 0, 0.005, 0.015, 0.045, 0.135, 0.405%) and Nisin (0, 0.25, 0.5, 0.75 μg/ml) and storage time (9 days) on the growth of Lactococcus garvieae Ir-170A(856bp) alone, and their combination in a food model system (fillets of the rainbow trout (Oncorhynchus mykiss). Additionally, the growth of a sample of this bacteria in laboratory conditions was studied.The results of this study showed that different concentrations of Nisin had a significant impact (p〈0.05) on Lactococcus garvieae.With the value of t in 0.75 μg/ml, the effectiveness rose to 65.77%; the biggest effect on Lactococcus garvieae. And the effect at 4 0C exceeded 80C.The study has also demonstrated that all concentrations of Zataria multiflora Bioss were effective against Lactococcus garvieae. However, with the value of t at 0.405%, the effectiveness was 71.91%. This value had the biggest effect on Lactococcus garvieae. At 4 0C, the effect surpassed the one at 80C.The synergistic effects of the EO and Nisin showed that with the value of t at 0.405% EO and 0.75 μg/ml Nisin was 14.62% had the greatest effect on Lactococcus garvieae.In this study, multi-factorial effects for different concentrations of Zataria multiflora Bioss (EO 0, 0.005, 0.015, 0.0025%), three different concentrations of122Nisin (0, 0.25,0.75 μg/ml) and two different levels of PH (5.5 , 7) at two incubation temperatures (15,37) on logp% of Lactococcus garvieae during 43 days in BHI broth were evaluated. Most of the effects on Lactococcus garvieae occurred in PH 5.5 and at a temperature of 150C.
    Description: PhD
    Description: Advisors: Mehdi Soltani, A. Akhondzadeh Basti. counsellor: A. Kamali
    Keywords: Aquaculture ; Chemistry ; Fisheries
    Repository Name: AquaDocs
    Type: thesis
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  • 17
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    Islamic Azad University, Science and Research Branch, Tehran, Fisheries
    In:  http://aquaticcommons.org/id/eprint/19304 | 17408 | 2016-02-08 10:30:38 | 19304 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-07-14
    Description: The main aim of this research was to identify fatty acids composition of Caspian sea of White fish Rutilus frisi kutum tissue and their changes during one year cold storage (-18Ċ).The secondary aim was to determine the changes of moisture, ash, protein, fat, and to investigate the effects of storage time on peroxide, TBAi, FFA, and extractability of myofibrillar proteins of the fish tissue during one year cold storage (-18 Ċ). 10 samples of (Rutilus frisi kutum) were randomly collected from Anzali landings. The samples were frozen at -30 Ċ and kept in cold storage at -18Ċ for one year. According to time table, the samples were examined. The results showed that 27 fatty acids were identified. The unsaturated fatty acids (UFA) and saturated fatty acids (SFA) were 74/09 and 21/63 %, respectively, in fresh tissue. So that DHA (C22:6) oleic acid (C18:1c) had high amounts (15/07 ,20/57 ) among the UFA and palmitic acid (C16:0) was the most (13/09 %) among the SFA. The effects of freezing and cold storage on fish tissue showed that UFA and SFA contents have reached to 58/79 and 22/17 %, respectively, at the end of cold storage. It indicated that these compound change to each other during frozen storage. Also ω-3 and ω-6 series of fatty acids was 24/22 and 15/56% in fresh tissue, but their contents decreased to 8/68 and 5/11% at the end of period. Among the fatty acids C22:6, C18:1c and C16:0 had the most changes. The changes of fatty acids were significantly at 95% level expected for C18:0. Results showed that moisture, ash, protein, and fat contents were 75/9±0/03, 1/28±0/012, 21/8±0/2, and 4/1±0/01 % respectively, in fresh tissue. The moisture, ash, protein, and fat contents were 72/3±0/04, 1/83±0/05, 1/91±0/01 and 19/9±0/01 % respectively, at the end of storage period. Lipid damage was measured on the basis of free fatty acids (FFA), peroxide value (PV), and Thiobarbituric acid index (TBA-i). PV, TBARS and FFA concentration of frozen Caspian Sea white fish stored at -18 Ċ the temporal variation of these three variables were statistically significant (p〈0.001). Results of White fish myofibrillar proteins showed aggregation of bound reduced for stored at 12 months. SDS-PAGE analysis revealed that, the intensity of the myosin heavy chain and actin bound was reduced with increasing storage time. SDS-PAGE patterns showed that myosin heavy chain was much more susceptible to hydrolysis than actin.Key words: Rutilus frisi kutum, frozen storage, ω-3, ω-6, protein myofibrillar
    Description: PhD
    Description: Advisors: Sohrab Moeini, Nasser Ghaemi Counsellors: A.K. Haghdost
    Keywords: Chemistry ; Fisheries
    Repository Name: AquaDocs
    Type: thesis
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  • 18
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    Islamic Azad University, Science and Research Branch, Tehran, Fisheries
    In:  http://aquaticcommons.org/id/eprint/19186 | 17408 | 2016-02-06 09:46:24 | 19186 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-07-13
    Description: In this study microbiological , chemical quality and fatty acid composition ofgrass carp (Ctenopharyngodon idella) fillets treated by dipping in sodiumacetate (%1 and %3), nisin (% 0.1 and % 0.2) and combination of sodiumacetate and nisin was evaluated during 16 days of refrigerated of 4°CAntilisterial effect of nisin was enhanced with the increased concentration ofsodium acetate. At day 12 post storage, Listeria monocytogenese count washigher in the control group than the recommended value, however in sodiumacetate and nisin treated samples, the count was lower (5.17-5.91 log cfu/g).With increasing the concentrations of sodium acetate, mesophilic counts werelower. Regarding nisin, better results was obtained by applying %0.1 nisin.Greater inhibition of mesophile bacteria was observed when combinationtreatment was used. The number of lactobacillus was lower when higherconcentrations of sodium acetate and nisin were used.Total Volatile Nitrogen values at the end of the experiment were lower in thesamples treated with both nisin and sodium acetate and the better results wereobtained in combination treatments. Peroxide (PV) at the end of the experimentwas 1.9 meq/kg in control, and the lowest values were observed for thetreatments 3(%0 sodium acetate +% 0.2 nisin) and 9(%3 sodium acetate +% 0.2nisin) between 1.08 and 1.62 meq/kg without significant difference.Thiobarbituric acid (TBA) levels at the end of experiment have been shown tobe 0.46 mg malonaldehyde per kg in the control. On the other hand treatments 9had the TBA values of 0.19 mg malonaldehyde per kg which was significantlylower than that of control.Polyunsaturated fatty acids increased by increasing the sodium acetate dosesand instead saturated fatty acids and n-6/n-3 ratio decreased. The ratio ofUFA/SFA and also C22:6/C16:0 increased when a higher concentration ofsodium acetate has been used. The best result obtained by using 3% of sodiumacetate but no such relation with nisin was observed.
    Description: PhD
    Description: Advisors: Mehdi Soltani, Abolghasem Kamali Counsellors: Mohammad Reza Ghomi, Seyed Ebrahim Hoseini
    Keywords: Chemistry ; Fisheries
    Repository Name: AquaDocs
    Type: thesis
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  • 19
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    Islamic Azad University, Science and Research Branch, Tehran, Fisheries
    In:  http://aquaticcommons.org/id/eprint/19182 | 17408 | 2016-02-06 09:57:11 | 19182 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-07-13
    Description: Effects of different thawing method i.e. in a refrigerator, in water, at air ambient temperature and in a microwave oven on proximate, chemical (PV, TBA, FFA, TVB-N, SSP, FA), biochemical (pH, WHC,ThL), microbial (total viable, psychrotrophic, coliform, Shewanella and yeast-mould count) and sensory analysis were carried out on frozen whole Caspian sea Kutum (Rutilus frisii kutum) and Rainbow trout (Oncorhynchus mykiss) carcasses. The values of ash, protein, SSP, WHC, PUFA, PUFA/SFA. EPA+DHA/C16:0, pH, and microbial count of thawed samples decreased significantly while fat, PV, TBA, FFA, TVB-N, SFA and MUFA increased compared to the fresh fish (unfrozen) as control samples. Also, sensory evaluation all of thawed samples showed a significant (p〈0.05) quality loss compared to the fresh fish as control samples. The lowest chemical and biochemical values as well as microbial growth were determined in water thawed samples. Therefore, based on this study thawing in water is most suitable for frozen whole rainbow trout.
    Description: PhD
    Description: Advisors: Masoud Rezaei, Mehdi Soltani Counsellors: Mohammad Haghighi, Reza Pourgholam
    Keywords: Aquaculture ; Biology ; Chemistry
    Repository Name: AquaDocs
    Type: thesis
    Format: application/pdf
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  • 20
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    Islamic Azad University, Science and Research Branch, Tehran, Fisheries
    In:  http://aquaticcommons.org/id/eprint/19245 | 17408 | 2016-02-08 10:18:48 | 19245 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-07-13
    Description: There is an increasing demand in developing newer and safer methods in preserving food products.Among which herbal additives seem to attract evermore attention recently.the major advantage of herbal additives is due to their favorable aroma besides their antimicrobial effects and less expensive than chemical additives. Zataria multiflora Boiss is a native Iranian herb which is used vastly as a food preserver essential oils and also medical usage.Metabolites of harmless bacteria, such as Nisin are also known to be safe preservatives that have antimicrobial activity.However to establish the usefulness of natural antimicrobial preservatives, they must be evaluated alone and in combination with other preservation factors to determine whether there are synergistic effects in rigid media .In this study were evaluated the effects of different concentrations of Zataria multiflora (EO 0, 0.005, 0.015, 0.045, 0.135, 0.405 ,0.810 %) and Nisin(0, 0.15, 0.25, 0.75 μg/ml) and Storage time (up to 21 days) on growth of Staphylococcus aureus ATCC 6538 in a food model system(light salted fish of silver carp, Hypophthalmichthys molitrix).The results on growth of S. aureus were evaluated using SPSS 15.0 statistical software (SPSS 15.0 for windows, SPSS Inc.) and analyzed the logarithm of total count of the bacteria by Tukey Test. Results were considered statistically significant when P≤0.05.The growth of Staphylococcus aureus was affected significantly(P〈0.05) by EO and Nisin and also combinations of EO and Nisin.Samples treated with 0.135, 0.405 and 0.810% of thyme essential oil showed a significant decrease on the growth of the bacteria compared with an treated samples(P〈0.05). No significant difference was seen on the growth of S.aureus in samples treated with lower concentrations of Z.multiflora(below 0.045%) and untreated group(P〉0.05).The most inhibitory effects were seen in samples treated with 0.405% and 0.810% of thyme essential oil until 9 and 12 days after storage,respectively.Also there was significant inhibtory effect(P〈0.05) in different concentration of nisin on the organism compared with an treated samples.The synergism effects of the Eo and nisin on the growth rate of the bacteria was significant (P〈0.05) compared with untreated samples and samples treated with the Eo or nisin, only. Synergismic effects was observed at concentration of 0.405 and 0.810% of Z. multiflora essential oil with 0.25 μg/ml Nisin, respectively until 15 days after storage.As expected it is preferred to apply the least possible amounts of additives in food preserving that not only are effective and safe but are economically justifiable.
    Description: PhD
    Description: Advisors: Afshin Akhondzadeh Basti, Mehdi Soltani counsellors: Abbas Matinfar
    Keywords: Aquaculture ; Chemistry ; Fisheries
    Repository Name: AquaDocs
    Type: thesis
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  • 21
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    Islamic Azad University, Science and Research Branch, Tehran, Fisheries
    In:  http://aquaticcommons.org/id/eprint/19144 | 17408 | 2016-02-06 09:40:52 | 19144 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-07-13
    Description: The present study aimed production of a new product with various texture and sensoryproperties in chase of the impetus for increasing human consumption considering suitableresources of Kilka fish in Caspian Sea. Following deheading, gutting, and brining, commonKilka were battered in two different formulations, i.e. simple batter and tempura batter, viaautomated predusting machinery and then, they were fried through flash frying for 30 secondsat 170°C in sunflower oil after they were breaded with bread crumbs flour. The products weresubjected to continuous freezing at -40°C and were kept at -18°C in cold storage for fourmonths once they were packed. Chemical composition (protein, fat, moisture, and ash), fattyacid profiles (29 fatty acids), chemical indices of spoilage (peroxide value, thiobarbituric acid,free fatty acids, and volatile nitrogen), and microbial properties (total bacteria count andcoliform count) were compared in fresh and breaded Kilka at various times before frying (rawbreaded Kilka), after frying (zero-phase), and in various months of frozen storage (phases 1,2, 3, and 4). Organoleptic properties of breaded Kilka (i.e. odor, taste, texture, crispiness,cohesiveness of batter) and general acceptability in the phases 0, 1, 2, 3, and 4 were evaluated.The results obtained from chemical composition and fatty acid profiles in common Kilkadenoted that MUFA, PUFA, and SFA were estimated to be 36.96, 32.85, and 29.12 g / 100glipid, respectively. Levels of ù-3 and ù-6 were 7.6 and 1.12 g / 100 gr lipid, respectively.Docosahexaonoic acid (20.79%) was the highest fatty acid in PUFA group. ù-3/ù-6 andPUFA/SFA ratios were 7.6 and 1.12, respectively. The high rates of the indices and highpercentage of ù-3 fatty acid in common Kilka showed that the fish can be considered asinvaluable nutritional and fishery resources and commonsensical consumption of the speciesmay reduce the risk of cardiovascular diseases. Frying breaded Kilka affected overall fat andmoisture contents so that moisture content in fried breaded Kilka decreased significantlycompared to raw breaded Kilka, while it was absolutely reverse for fat content. Overall fatcontent in tempura batter treatment was significantly lower than that of simple battertreatment (P≤0.05). Presence of hydrocolloids, namely proteins, starch, gum, and otherpolysaccharides, in tempura batter may prohibit moisture evaporation and placement with oilduring frying process in addition to boosting water holding capacity through confining watermolecules. During frying process, fatty acids composition of breaded Kilka with variousbatters changed so that rates of some fatty acids such as Palmitic acid (C16:0), Stearic acid(C18:0), Oleic acid (C18:1 ù-9cis), and linoleic acid (C18:3 ù-3) increased considerablyfollowing frying; however, ù-3/ù-6, PUFA/SFA, and EPA+DHA/C16:0 ratios (Polyan index)decreased significantly after frying. ù-3/ù-6, PUFA/SFA, and EPA+DHA/C16:0 ratios intempura batter treatment were higher than those of simple batter treatment which is anindicator of higher nutritional value of breaded Kilka with tempura batter. Significantelevations were found in peroxide, thiobarbituric acid, and free fatty acids in fried breaded Kilka samples compared to raw samples which points to fat oxidation during cooking process.Overall microorganism count and coliform count decreased following heating process. Bothbreaded Kilka samples were of high sanitation quality at zero-phase according to ICMSFStandard. The results acquired from organoleptic evaluation declared that odor, cohesiveness,and general acceptability indices, among others, had significant differences between thetreatments (P≤0.05). In all evaluated properties, breaded Kilka with tempura batter indifferent phases gained higher scores than breaded Kilka with simple batter. During coldstorage of various treatments of breaded Kilka, total lipid content, PUFA, MUFA, ù-3, ù-3/ù-6, PUFA/SFA, Polyen index decreased significantly. The mentioned reductions inaddition to significant elevation of spoilage indices, namely peroxide, thiobarbituric acid, andfree fatty acids, during frozen storage, indicate to oxidation and enzymatic mechanismactivity during frozen storage of breaded Kilka. Considering sensory evaluation at the end ofthe fourth month and TVB-N contents exceeded eligible rate in the fourth month, shelf life ofthe products during frozen storage was set to be three months at -18°C. The results obtainedfrom statistical tests indicate to better quality of breaded Kilka processed with tempura battercompared to simple batter in terms of organoleptic evaluation, spoilage indices, and highquality of fat in various sampling phases.
    Description: PhD
    Description: Advisors: Ali Asghar Khanipour, Mehdi Soltani Counsellors: Abbasali Motallebi, Abolghasem Kamali
    Keywords: Chemistry ; Fisheries
    Repository Name: AquaDocs
    Type: thesis
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  • 22
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    Islamic Azad University, Science and Research Branch, Tehran, Fisheries
    In:  http://aquaticcommons.org/id/eprint/19118 | 17408 | 2015-12-14 19:22:20 | 19118 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-07-13
    Description: The purpose of this study, Evaluation the effect of Rosmarinus officinalis and Thymus vulgaris extracts on the stability of poly unsaturated fatty acids in frozen Silver carp minced. Treatments include:Treatment 1 - Control: frozen meat packaged in conventionalTreatment 2: Frozen Silver carp minced+Thyme 300 mg/kg in normal packagingTreatment 3: Frozen Silver carp minced+Rosemary 200 mg/kg in normal packagingTreatment 4: Frozen Silver carp minced+Rosemary compound (100 mg/kg) and Thyme(100 mg/kg) in normal packagingAfter rapid freezing of samples in the spiral freezer by individual quick freezing method, tomaintain the cold temperature (-18) °C were transferred. Sampling and measurements to determine the fatty acid profile of the zero phase beginning in the first month and then every ten days, and 15 days in the second month of the third month after the monthly test.Identifying, defining and measuring the fatty acid profile by gas chromatography was performed. In this study, levels of both saturated and unsaturated fatty acids in threeexperimental and one control were identified as follows:A: saturated fatty acids: Meristic C14: 0/Palmitic C16: 0/Hepta decaenoic C17: 0/Stearic C18: 0/Arashidic C20: 0/B:Mono unsaturated fatty acids: palmitoleic C16: 1-W7/Oleic C18: 1-W9/Gadoleic C20:1-W9C:Poly unsaturated fatty acids: Linoleic C18: 2-W6/α-Linolenic C18: 3-W3D:High unsaturated fatty acids: Arachidonic C20: 4-W6 Eicosapentaenoic acid C20: 5-EPA/W3 Docosahexaenoic C22: 6-DHA/W3Results of this study was to determine, Thyme and rosemary extracts containing silver carpminced stored in freezing conditions, Stability of different types of fatty acids, monounsaturatedfatty acids, poly-unsaturated fatty acids, omega-3 and omega-6 fatty acids are. So that none of the fatty acids measured were not significant 100% increase or decrease,While changes in the fatty acid oxidation during storage time is minimized. The resultsobtained from the fatty acid profiles and indicators of their and statistical tests show that treatment with rosemary extract More stable during storage (-18) ° C In comparison with the control and other treatments are shown; And at relatively low compared to othertreatments and control samples oleic acid and linoleic acid, palmitic more.According to studies,in Silver carp minced that containing rosemary extract, end of the storage period of six months. Were usable, so even rosemary extract the shelf-lifeexamples to increase more than six months.
    Description: PhD
    Description: Advisors: A. A. Motalebi Moghanjvqy, Seyed Ebrahim Hosseini Counsellors: Ali Asghar Khanipour, Mehdi Soltani
    Keywords: Agriculture ; Chemistry ; Fisheries
    Repository Name: AquaDocs
    Type: thesis
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  • 23
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    Islamic Azad University, Science and Research Branch, Tehran, Fisheries
    In:  http://aquaticcommons.org/id/eprint/19141 | 17408 | 2016-02-01 21:04:45 | 19141 | Islamic Azad University, Science and Research Branch, Tehran
    Publication Date: 2021-07-13
    Description: Nisin is a widely used naturally occurring antimicrobial effective against many pathogenic and spoilage microorganisms. It has been proposed thatreduced efficacy of nisin in foods can be improved by technologies such as encapsulation to protect it from interferences by food matrix components. Theaim of this study was using of spray dried encapsulated nisin with zein in concentration of (0.15 and 0.25 g/kg) and sodium citrate (1.5 and 2.5%) and treatments with both of them to extent the shelf life of filleted trouts packagedby Modified Atmosphere Packaging (45% CO2, 50% N2 ,5% O2) and stored at 4±1 °C for 20 days. Furthermore, to evaluate the antimicrobial efficiency of encapsulated nisin and soudium citrate the trouts fillets was inoculated withStaphylococcus aureus as an index pathogenic bacteria. Assessment of chemical spoilage indexes such as (Proxide value, Thiobarbituric acid, total volatile basenitrogen and pH) , microbial parameters (Total Plate Count, Psychrotrophic count, Lactic acid bacteria count), Staphylococcus aureus cont in treatments which were inoculated with 5 logcfu/g of this bacteria and sensory evaluation of fillets including (smell, color, texture and total acceptability) was carried out indays of 0, 4, 8, 12, 16 and 20. The results revealed that treatment with both exposure of nisin and sodium citrate showed significantly lower chemicalspoilage indexes in comparison with controls (vaccum packed and MAP)(P〈0.05). Furthermore, (nisin 0.25 g/kg sodium citrate 2.5%) treatment whichwas exposed to the maximal level used of both materials was significantly thelowest treatment with (Proxide value, Thiobarbituric acid, total volatile basenitrogen and pH) of 9.95 (meq O2/kg) , 1.55 (mgMA/kg), 29.65 (mgN/100g) and 6.65 , respectively and according to the maximal recommended level of this indices , shelf life of fillets in this treatment was esstimated 20 days.The control(vaccum packed) treatment was significantly the highest treatment with (Proxide value, Thiobarbituric acid, total volatile base nitrogen and pH) of 15.17 (meq O2/kg), 3.03 (mgMA/kg), 38.4 (mgN/100g) and 6.95 , respectively and according to the maximal recommended level of this indices , shelf life of filletsin this treatment was estimated 11 days. Also, in microbial point of view (nisin0.25 g/kg- sodium citrate 2.5%) treatment was the lowest treatment with TotalPlate Count, Psychrotrophic count, Lactic acid bacteria count andStaphylococcus aureus count of 6.7, 6.83, 5.25 and 6.04 logcfu/g respectively,and conrol (vaccum packed) treatment was the highest treatment with 9.15, 9.41, 7.7 and 9.01 logcfu/g respectively. According to the lower results of chemicaland microbial indices and higher sensory evaluated scores assessed in this research for encapsulated nisin in comparison with free nisin , it was concludedthat encapsulation of nisin with zein capsules may improve the efficiency of nisin. The measuremented values of Mass yield, Total solids content of capsules, Encapsulation efficiency, In vitro release kinetics in 200 hour for encapsulated nisin in this study was 49.89, 62, 98.31 and 69% respectively and Encapsulated particle size was lower than 674.21 μm for 90% of particles. As a consequence, nisin , in particular encapsulated nisin, and sodium citrate alone or together with and Modified Atmosphere packaging might be considered as effective tools in preventing the quality degradation of the fillets, resulting in an extension of their shelf life.
    Description: PhD
    Description: Advisors: Seyed Ebrahim Hosseini, Aboulghassem Kamali Counsellorrs: Abbasali Motallebi, Resa Pourgholam
    Keywords: Aquaculture ; Chemistry ; Fisheries
    Repository Name: AquaDocs
    Type: thesis
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  • 24
    Electronic Resource
    Electronic Resource
    Springer
    Accreditation and quality assurance 5 (2000), S. 409-413 
    ISSN: 1432-0517
    Keywords: Key words Metrology ; Comparisons ; Chemistry ; Standards
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  After stressing the importance in the modern world of accurate and reproducible measurements, the actions taken by the Bureau International des Poids et Mesures to set up, together with the regional metrology organizations, a series of key comparisons are described. They are the technical foundation of a mutual recognition of national measurement standards arrangement prepared in conjunction with the National Metrology Institutes (NMIs). This arrangement also includes the recognition of calibration and measurement certificates issued by these institutes. Then, the consequences of this arrangement for trade are described. The case of chemical analysis is illustrated by the application of the Kyoto protocol on the reduction of greenhouse gases. But the global workload to be taken up by the International Committee of Weights and Measures, its Consultative Committee for Amount of Substance and the NMIs is huge.
    Type of Medium: Electronic Resource
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  • 25
    Electronic Resource
    Electronic Resource
    Springer
    Earth, moon and planets 88 (2000), S. 35-58 
    ISSN: 1573-0794
    Keywords: Chemistry ; interplanetary dust particles (IDPs) ; Leonids ; meteor trails ; meteoroids ; meteors ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The cometary Leonid meteoroids represent a size range in between largest carbon-richIDPs and the smallest CI meteorites. Their dustball structure and chemistry offer anopportunity to constrain hierarchical dust accretion inferred from petrologic studies ofaggregate and cluster IDPs. The Leonid shower meteoroids of known ``comet ejection''ages provide an opportunity to study space weathering of cometary dust over periodsof up to several hundred years. The meteors and aggregate and cluster IDPs displaycontinuous thermal modification of organics and volatile element (Na, K-bearing phases), that occur as discrete minerals and amorphous solids each different response during kinetically controlled ablation. Leonid meteoroids are not excessively Na-rich. The occurrences of Leonid meteors can now be accurate predicted and combined withknowledge better models for the settling rates, collections of surviving dust becomea comet nucleus-sampling mission.
    Type of Medium: Electronic Resource
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  • 26
    ISSN: 1432-0975
    Keywords: Key words Otolith ; Chemistry ; ICP-MS ; Stock discrimination ; Epinephelus striatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract  We examined the utility of otolith minor and trace element chemistry, assayed with inductively coupled plasma mass spectrometry (ICP-MS), as a means of delineating population structure in the Nassau grouper (Epinephelus striatus). We characterized the elemental composition of otoliths collected in 1993 from three locations in Exuma Sound, Bahamas and from Glover Reef, Belize in 1995. A single location in Exuma Sound was sampled in 1994 to test temporal variability in otolith composition. Five elements (Ca, Zn, Sr, Ba and Pb) were routinely detected, at levels significantly above background, by solution-based ICP-MS. Results from analysis of variance of elemental data, expressed as a ratio to Ca, indicated that there were no significant differences among the Exuma locations for any element, but significant variability was found between Glover Reef and the pooled Exuma localities for Zn/Ca, Sr/Ca and Ba/Ca ratios. Significant inter-annual differences at one Exuma Sound location was restricted to Ba/Ca ratios. Discriminant function analysis correctly classified 86% and 95% of the Belize and pooled Exuma sites, respectively. Otoliths from Belize were characterized by low Zn/Ca and high Ba/Ca and Pb/Ca ratios compared to otoliths from fish collected in Exuma Sound. Although differences in Ba levels may be related to upwelling at Glover Reef, more data are needed to definitely link otolith composition with regional differences in water chemistry.
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  • 27
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    Chromatographia 49 (1999), S. 543-546 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; MS-MS detection ; Electrospray-Ionization (ESI) ; Beer ; Ochratoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Ochratoxin A (OTA) is a nephrotoxic and nephrocacinogenic mycotoxin commonly produced by several ubiquitousAspergillus andPenicillium species. OTA is found predominantly in cereals and derived products, and therefore OTA may be transferred into beer from contaminated grain. Thirty-five samples of German beers were analyzed: OTA was extracted with toluene and purified by solid phase extraction using silica cartridges. OTA was determined by high-performance liquid chromatography with fluorescence detection. Since of fluorescence detection is not specific in this instance, the beer samples were also analyzed by high-performance liquid chromatography electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS). OTA levels in the range of 0.1–0.2 μg L−1 were found in 9 beer samples, 21 samples contained trace amounts of OTA (〈0.1 μg L−1) and in 5 samples no OTA was detectable.
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  • 28
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solid phase extraction ; Doxorubicin ; Cell culture media ; Human plasma ; Fluorescence detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Doxorubicin is an antineoplastic antibiotic isolated fromStreptomyces peucetius var.cesius clinically used in the treatment of tumors such as lung or breast, Hodgkin's disease and various types of leukemias. The main goal of this study was to develop a simple and sensitive HPLC method with fluorescence detection for the quantitation of doxorubicin in cell culture media collected during an in vitro studies and in human plasma. Solid phase extraction (C2 silica) was applied. The experiment established five-point standard curve (1 ng mL−1 to 100 ng mL−1). The standard curves prepared in blank cell tissue media were linear over the range of doxorubicin assayed and had a mean correlation coefficient of 0.9973±9.43×10−4 and slope 0.02545±1.85×10−3. The standard curves prepared in human plasma were linear and had mean correlation coefficient of 0.997 and slope 0.01885±5.19×10−4. The limit of quantitation for doxorubicin in both specimens was arbitrarily established to be 1 ng mL−1. Intra-day variabilities were determined using 3–4 replicates of control solutions of doxorubicin (3 ng mL−1 and 30 ng mL−1) in blank plasma and cell culture media. Inter-day variabilities were determined over a four day period analyzing replicates of controls. All precision and accuracy values fell within the acceptable range.
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  • 29
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Capillary zone electrophoresis ; Electrospray ionization-mass spectrometry ; Human serum albumin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Human serum albumin (HSA) is one of the most abundant human proteins and has been shown to be heterogeneous. A RP-HPLC method has been developed to separate HSA components in commercially available preparations. Separations were carried out on Aquapore RP-300, C8 columns using gradient elution with a combination of acetonitrile/water mobile phases containing 0.05% trifluoroacetic acid as ion-pairing agent. Optimum resolution was attained on narrow-bore columns using a stepwise, linear gradient that incorporated a shallow intermediate step of 0.20%/min in Mobile Phase B. Under similar elution conditions, separations carried out on standard-size columns showed the expected decrease in resolution due to increased peak widths. A comparative analysis of three commercial products highlighted qualitative and quantitative differences. Capillary zone electrophoresis was used for the analysis of collected RP-HPLC fractions. Results indicated that while the HPLC separation was incomplete, one of the major HPLC peaks was primarily composed of one of the three main components typically separated by CZE. ESI-MS was used to characterize the two major RP-HPLC fractions and also showed that the HPLC separation was incomplete. The MaxEnt transform of the HPLC peaks was consistent with components all being HSA and closely related derivatives.
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  • 30
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amino acids ; FMOC derivatives ; Oligopeptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary One classical method for quantitation of amino acids in proteins is hydrolysis of the proteins and determination of the free amino acids. Although the drastic experimental conditions necessary for complete hydrolysis always cause degradation of some of the amino acids, if mild hydrolysis conditions are used, a mixture of amino acids and oligopeptides is obtained. If these conditions are adequately tuned, the oligopeptides are almost exclusively dipeptides. For this reason we have initiated a study to find a derivatizing agent suitable for the analysis of amino acids and dipeptides by an absolute method of quantitation already tested for amino acids. FMOC-Cl was found to be a suitable derivatizing agent for this purpose.
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  • 31
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    Chromatographia 49 (1999), S. 369-373 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Sep-Pak CN cartridge ; Oxytetracycline ; Sulphadimidine ; Meat and eggs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid method for the simultaneous determination/identification of residual oxytetracycline (OTC) and sulphadimidine (SDD) in meats (beef, pork, chicken) and eggs by high-performance liquid chromatography (HPLC) was developed. The extraction of OTC and SDD was performed using a Sep-Pak® CN cartridge. The extracts contained OTC/SDD analytes when examined by HPLC using a LiChrospher® 100 RP-8 end-capped column and a mobile phase of acetonitrile-acetic acid-water (28:4:68, v/v/v) with a photodiode array detector. The average recoveries from spiked samples (0.1 μg g−1 and 1.0 μg g−1) were in excess of 80.2% with coefficients of variation between 1.5 and 5.0%. The limits of detection for OTC and SDD were 0.05 and 0.02 μg g−1, respectively.
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  • 32
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Evaporative light-scattering detection ; MALDI-TOF ; Polyethylene glycols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polyethylene glycols (PEGs) of nominal molecular weight (M) 200, 400, 600, 1000, 1500, 3000, 4000 and 6000 were chosen as model compounds and subjected to reversed-phase high performance liquid chromatography (RP-HPLC) on an octadecasilyl silica gel (C18) stationary phase using a binary gradient composed of acetonitrile and water and evaporative light scattering detection (ELSD). Satisfactory resolution of oligomers up to M of 3000 was accomplished; the higher M samples PEG-4000 and PEG-6000 could not be further resolved into the constituent oligomers and therefore, M=4000 marks the upper limit of oligomer resolution. Despite some peak overlapping as a consequence of the more or less broad oligomer distribution, individual types of PEG samples can be distinguished from each other by their characteristic chromatographic fingerprint patterns, as shown with a mixture consisting of PEG-400, PEG-1000, PEG-3000, PEG-4000 and PEG-6000. For this reason, the method is well-suited for characterization of samples containing PEGs widely differing in M. In addition, matrix assisted laser desorption ionization time of flight mass spectroscopy (MALDI-TOF/MS) performed with PEG-600, PEG-1000 and PEG-3000 revealed that the optimum degree of oligomer resolution has been achieved by use of the present method.
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  • 33
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral stationary phases ; Crown ether derivatives ; Amino compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The enantiomers of primary amino compounds have previously been resolved on a chiral stationary phase (CSP) CSP-18C6I, prepared by immobilizing (+)-18-crown-6 tetracarboxylic acid. In this study related chiral stationary phases were prepared in an effort to broaden the scope of CSP18C6I. CSP-18C6II, synthesized to investigate the effect of spacer length, resolved the enantiomers of 2-amino-1,2-diphenylethanol and 1-(1-naphthyl)ethylamine (1-NEA) (hydrophobic amino compounds) with the largerk values and smaller α values than on CSP-18C6I, probably because of the greater hydrophobicity of CSP-18C6II. Use of CSP-18C6III, synthesized by modification of carboxylic acid functionality of CSP-18C6II by introduction of another chiral moiety,S-1-NEA, resulted in larger α values for 2-amino-1-phenylethanol and 2-amino-1-phenylpropanol than on CSP-18C6II, but the enantiomers of 1-NEA were not resolved, because of steric hindrance between 1-NEA and the chiral moiety. The amide derivativeN-3,5-dinitrobenzoyl-1-(α-naphthyl)ethylamine (DNN) as π-acceptor (3,5-dinitrobenzoyl function) or π-donor (naphthylethylamide function), and no primary amino functionality, was resolved on CSP-18C6III. The mechanism of separation of the enantiomers of DNN was assumed to be the π−π interaction between the 3,5-dinitrobenzoyl function (π-acceptor) of DNN and theS-1-NEA moiety (π-donor) of CSP-18C6III.
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  • 34
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Alcohols ; Pre-column fluorescence derivatization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sensitive LC method for the determination of alcohols, using fluorescent condensation agent carbazole-9-N-acetylbenzne-disulfonate(CABS), has been developed. A mixture of alcohols and triethylamine catalyst in dichloromethane or chloroform is treated with CABS to give quantitative yields of esters. Emission maximum for the derivatized alcohols is 365 nm (λex 335 nm). The labeled derivatives are very stable, no significant decomposition is observed after heating in 40% at 40°C for 24 h. The method, in conjunction with a multigradient program, offers baseline resolution of common alcohol derivatives on a reversed-phase C18 column. Studies on derivatization conditions indicate that primary and secondary alcohols react very fast with CABS in the presence of triethylamine in dichloromethane or chloroform to give the corresponding fluorescent derivatives. This method is more convenient and more efficient than previous methods which require prior conversion of carboxylic acids to acyl chlorides. The separation of alcohol derivatives has good reproducibility and the rsd's (n=5) for 50 pmol of each alcohol are 4%. Detection limits are at the fmol level.
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  • 35
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    Chromatographia 49 (1999), S. 42-46 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral resolution ; Jasmonic acid ; Plant growth regulators ; Amine conjugates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Racemic jasmonic acid (3R,7R/3S,7S)-(±)-JA) was chemically conjugated with different biogenic amines originating from aliphatic and aromatic α-amino acids by decarboxylation. The resulting isomeric compounds were subjected to reversed-phase high-performance liquid chromatography (HPLC) and to HPLC on the chiral stationary phases Chiralpak AS and Nucleodex β-PM. Under reversed-phase conditions, all the homologous amine derivatives tested could be separated from each other except the JA-conjugates containing 2-phenyl-ethylamine and 3-methylbutylamine. On both chiral supports the (3R,7R)-(−)-JA conjugates eluted earlier than those of the enantiomeric counterpart (3S,7S)-(+)-JA. On Chiralpak AS all the isomers studied could be separated to baseline with a mobile phase containingn-hexane and 2-propanol. The calculated resolution factors were between 1.80 and 4.17. The pairs of isomers were also chromatographed on the cyclodextrin stationary phase Nucleodex β-PM with methanol-triethylammonium acetate buffer as mobile phase. Under these conditions resolution factors were between 0.74 and 1.29. The individual isomers were chiroptically characterized by measurement of their circular dichroism.
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  • 36
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micellar electrokinetic chromatography (MEKC) ; Oral contraceptives ; Ethinylestradiol ; Gestodene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A micellar electrokinetic chromatographic method is presented which permits quantification of ethinylestradiol and gestodene in pharmaceutical products. Separation was carried out at 25°C and 25 KV, using a 20 mM borate buffer (pH 9.2), 15 mM sodium dodecylsulfate in 30% acetonitrile-water (v/v). Under these conditions analyses were carried out in 7 min. Four different oral contraceptives were analysed and the results compared favourably with those of a reference liquid chromatographic method.
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  • 37
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Zirconium oxide ceramics ; X-ray fluorescence ; Neutron activation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Lanthania-and yttria-stabilized zirconium oxide ceramics have been examined using High Performance Liquid Chromatography (HPLC), thermal neutron activation (NA) and X-ray Fluorescence (XRF) analyses and thus determine the stabilizer content. Ceramic powders with the composition ZrO2:x mol % La2O3 (x=5, 10, 15, 20 and 33) and ZrO2:x mol % Y2O3 (x=10, 15, 20 and 25) were prepared by the citrate and the co-precipitation techniques, respectively. The lanthanum content was determined by HPLC (x=5.09, 9.78, 14.98, 19.81 and 25.94) and NA (x=5.15, 10.32, 17.25, 21.08 and 27.97) analyses, the yttrium content by HPLC (x=8.5, 13.5, 17.9 and 22.1) and XRF (x=9.9, 15.8, 20.1 and 24.9) analyses. An experimental sequence, based on continuous dilution of ceramic powder solutions, is proposed for preparing samples for HPLC measurements. A swimming pool nuclear reactor is used for NA analysis. The quantitative determinations of yttrium and lanthanum doping levels obtained using those techniques are described.
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  • 38
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; α-Chymotrypsin immobilized on silica ; In situ immobilization process ; Structural chiral separations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary α-Chymotrypsin was immobilized on an epoxide derivatized silica gel by anin situ immobilization process. Several racemates were resolved by a structural recognition mechanism. The immobilization process and the stability of this α-chymotrypsin stationary phase have been studied. The mobile phase parameters including the ionic strength, pH and the effects of organic modifiers have been also investigated. The retention, efficiency and stereoselectivity of the solutes appear to be related to their molecular structure, hydrophobicity and electrostatic interactions. These relationships determine the recognition mechanism and the position of each enantiomer in the active site.
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  • 39
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Enantiomer separation ; Chiral-AGP column ; Idrapril ; Temperature effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A direct liquid-chromatographic method has been developed for the stereoselective analysis of idrapril and its stereoisomers on a chiral α1 glycoprotein (AGP) column. The influence of flow-rate, temperature, and mobile phase composition on retention and selectivity was evaluated to find the optimum conditions for chiral separation.
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  • 40
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polyfluoroalkyl-coated silica ; 29Si CP/MAS NMR ; Polyaromatic compounds ; Fluorinated compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The conditions for reaction of the branched polyfluoroalkylsilane D3CL with silica gel have been examined. From elemental analyses and29Si NMR spectra it was found that the surface coverage and endcapping of D3CL-coated silica gel (Fluofix®) were the same as for ODS packings. The separation behavior of these phases was compared that of a variety of other packings. For polyaromatic compounds and benzene derivatives Fluofix worked in the reversed-phase mode and its retention characteristics were similar to those of C1 or CN packings. For fluorinated compound the retention characteristics of the phases is similar to those of ODS although with MeOH-water and MeCN-water mobile phases the pressure loss was lower for the fluorinated phases than for ODS.
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  • 41
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    Chromatographia 49 (1999), S. 699-702 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Anion-exchange chromatography ; High ph elvents ; Monosaccharides ; Carbopac PA-100
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary We have studied the elution behaviour of six common monosaccharides, fucose, galactosamine, glucosamine, galactose, glucose and mannose, on the CarboPac PA-100 column. The relative elution positions of galactose, glucose and mannose were dependent on the sodium hydroxide concentrations, a phenomenon which was likely to be the result of differential ionisation of the hydroxyl groups at ring positions two and four. The optimal resolution of the monosaccharides studied was achieved by elution with 30 mM sodium hydroxide with no appreciable loss in sensitivity at this low concentration.
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  • 42
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Meropenem in human plasma ; Solid phase extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper describes an HPLC method for the determination of meropenem in human plasma. The method uses solid phase extraction (SPE) of the samples and has good sensitivity, precision and accuracy. The limit of quantification in plasma samples is 0.02 μg mL−1. Calibration curves were linear over a large dynamic range, namely within 0.02–50 μg mL−1. The method was applied to the determination of meropenem levels in patients receiving meropenem, as a single dose or at steady state.
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  • 43
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    Chromatographia 49 (1999), S. 12-16 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fatty alcohol sulfates ; Alkyl polyglycosides ; Trace analysis ; Steam distillation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Acid catalyzed hydrolysis of fatty alcohol sulfates under reflux condition or by microwave heating is compared. Microwave hydrolysis turned out to be faster and more convenient to use. The combination of reflux hydrolysis of fatty alcohol sulfates or alkyl polyglycosides and the simultaneous steam distillation of the generated fatty alcohols gives a very powerful sample preparation and enrichment method for fatty alcohol sulfates and alkyl polyglycosides. The preconcentrated fatty alcohols are derivatized and detected via fluorescence detection. The applicability of the method is demonstrated by the analysis of fatty alcohol sulfates in cosmetics and in river water as matrices spiked with approximately 4 ppb fatty alcohol sulfates.
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  • 44
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; DAD and MS detection ; Liquid-solid extraction ; Catechin derivatives ; Myricetin derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A liquid-solid extraction and purification procedure (LSE) was developed to identify and quantify polyphenols in the leaf tissue ofMyrtus communis L. Identification and quantitation of individual compounds was performed using HPTLC, HPLC-DAD and HPLC-MS analysis. Leaves ofMyrtus communis L. contain small amounts of phenolic acids (caffeic, ellagic and gallic acids) and quercetin derivatives (quercetin 3-O-galactoside and quercetin 3-O-rhamnoside), whereas catechin derivatives (epigallocatechin, epigallocatechin 3-O-gallate, epicatechin 3-O-gallate) and myricetin derivatives (myricetin 3-O-galactoside, myricetin 3-O-rhamnoside) are present in large amounts. This is the first report on the occurrence of galloyl-derivatives of catechin and gallo-catechin inMyrtus communis L. leaves.
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  • 45
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Glycolytic enzymes ; p-Hydroxymercuribenzoate ; 203Hg-labelledp-hydroxymercuribenzoate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of hydrophobic-interaction chromatography (HIC) is proposed for the simultaneous determination of more than one thiol-protein after formation of the corresponding mercury mercaptides withp-hydroxymercuribenzoate (PHMB). The new chromatographic procedure, based on the HIC separation of the modified proteins from each other and from excess organomercury reagent has been successfully applied to the quantitative determination of phosphoglucose isomerase (PGI) and phosphoglucose mutase (PGM) in crude PGI powder, and of L-lactate dehydrogenase, PGM and aldolase in crude pyruvate kinase from rabbit muscle. The suitability of203Hg-labelled PHMB has been tested in the analysis of mixtures, which give barely distinguishable UV-peaks owing to the presence of other non-thiol components in the sample. For this purpose glyceraldehyde 3-phosphate dehydrogenase (GAPDHy) and PGIy from bakers yeast have been considered. Results obtained in experiments performed by both procedures are reported.
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  • 46
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral stationary phases ; Benzophenone imine derivatives ; Amino acid esters ; Enantiomer separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The liquid-chromatographic separation of the enantiomers of amino acid esters as benzophenone Schiff-base derivatives on polysaccharide-derived chiral stationary phases (CSPs) is described. The performance of Chiralcel OF was superior to that of the other CSPs for resolution of benzophenone imine derivatives of amino acid ethyl and methyl esters. The enantiomers of most of the amino acid esters examined as their benzophenone imine derivatives were resolved to baseline on Chiralcel OF. The L-(−) enantiomers of all the analytes were preferentially retained on Chiralcel OF. The resolution of several imine derivatives of amino acid esters was investigated, as was the effect of eluent composition on the resolution of amino acid ethyl esters as their benzophenone imine derivatives.
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  • 47
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amperometric detection ; Clozapine ; Desmethylclozapine ; Drug monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high-performance liquid chromatographic method with amperometric detection has been developed for the determination of levels of clozapine (CLZ) and its active metabolite N-desmethylclozapine (DMC) in human plasma. The analysis was performed on a 5 μm C8 reversed phase column (150×4.6 mm i.d.), with acetonitrile-phosphate buffer (pH 3.5), as the mobile phase. The detection voltage was +800 mV and the cell and column temperature were 50°C. Linear responses were obtained between 2 ng mL−1 and 100 ng mL−1. Absolute recovery for both clozapine and desmethylclozapine exceeded 88% and the detection limit was 1 ng mL−1. Repeatability, intermediate precision and accuracy were satisfactory. The method, which is rapid, sensitive and selective, has been applied to therapeutic drug monitoring in schizophrenic patients following administration of Leponex® tablets. In 21 patients in steady state at a mean daily clozapine dosage of 358 mg (ranging from 150 to 500 mg day−1), clozapine levels averaged 379 ng mL−1 (ranging from 102 to 818 ng mL−1) and DMC levels averaged 233 ng mL−1 (ranging from 70 to 540 ng mL−1). The method requires only a very small amount of plasma (100 μL), and thus it is suitable for pharmacokinetic studies, as well as for therapeutic drug monitoring.
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  • 48
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cyclodextrin additives ; Fluorescence agents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary We report four new derivatization agents, acridone-N-acetic acid (ARC), carbazole-9-ylacetic acid (CRA), carbazole-9-ylpropionic acid (CRP), and 2-methyl-2-carbazole-9-ylacetic acid (MCRA), with strong fluorescence emission which has low dependence on solvent polarity. The emission maxima for ARC, CRA, CRP, and MCRA were 430 nm (λex 404 nm), 368 nm (λex 335 nm), 356 nm (λex 340 nm) and 360 nm (λex 330 nm), respectively. The effects of mobile-phase composition, pH, and temperature on the liquid chromatographic retention behavior of the four fluorescence agents were investigated. An experimental model was established for calculating the inclusion constants of cyclodextrin (CD) complexes in the dynamic state, using β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) as examples, and different mobilephase compositions. On the basis of the model, the inclusion constants of the solutes in pure water (K fw) were determined by extrapolation. The thermodynamic parameters (ΔH o and ΔS o) and dissociation constantsK am for the solutes in this chromatographic system were obtained by means of capacity factor (k) values using a corresponding model formulation.
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  • 49
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Interaction of mobile and stationary phases ; Linear solvation energy relationships ; Triethylamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of triethylamine (TEA) in the mobile phase on the RPLC retention behavior of small organic solutes has been studied on a conventional polymeric octadecylsilica (ODS) and on a horizontally polymerized ODS. Retention factors for a set of solutes were measured on the two phases with methanol-water mobile phases containing triethylamine at different concentrations and analyzed by use of linear solvation energy relationships (LSER). Variation of the resulting LSER coefficients—v (hydrophobicity),r (polarizability),s (dipolarity),b (hydrogen-bond (HB) donating acidity), anda (HB accepting strength)—were examined to see how TEA affects the intermolecular interaction properties of the mobile and stationary phases and hence the retention of the solutes. Addition of TEA to the mobile phase changes the interaction properties of both conventionally polymerized and horizontally polymerized ODS; the effect is greater for the conventional phase. The HB donating acidity (b) of conventional polymeric ODS is significantly reduced by addition of TEA. For the mobile phases studied the magnitudes of theb andv coefficients for the horizontally polymerized ODS phase are greater than for the conventional phase. The different interaction properties of the two polymeric phases arise mainly as a result of differential adsorption of TEA, because of the very different amounts of surface silanol groups present on the two phases.
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  • 50
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; p-tert-Butyl-calix[4]arene-bonded silica ; Nuclear magnetic resonance spectrometry ; PAHs ; Nucleosides bases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method is proposed for preparation of ap-tert-butyl-calix[4]arene-bonded silica stationary phase. The chemically modifiedp-tert-butyl-calix[4]arene is attached to silica gel via the silane coupling reagent γ-(ethylenediamino)-propyl-triethoxyl-silane. The bonded phase has been characterized by29Si and13C cross polarization/magic angle spinning solid-state nuclear magnetic spectrometry. The retention behavior of polycyclic aromatic hydrocarbons (PAHs), nucleosides and bases has been investigated on the bonded phase in the reversed-phase mode.
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  • 51
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    Chromatographia 49 (1999), S. 671-677 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microwave hydrolysis ; Microcystin ; Nodularin ; D- and L-selective amino acid determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Microwave radiation has been successfully used for hydrolysis of the hepatotoxic cyclic peptides microcystins and nodularin. Set-up of the microwave device and the operating conditions for microwave hydrolysis were optimized. Results of the microwave hydrolysis were compared with results from conventional hydrolysis for 24 h at 110°C. Microwave hydrolysis of microcystins and nodularin for as little as 10 min at 160°C results in complete cleavage of peptide bonds and high recoveries of amino acids. Enantioselective determination of amino acids was achieved by use of a previously described HPLC method after pre-column derivatization withortho-phthaldialdehyde and the chiral thiolN-iso-butyryl-cysteine.
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  • 52
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Hydroxypropyl-β-cyclodextrin ; Imidazole derivatives ; Retention mechanisms ; Enthalpy-entropy compensation
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    Topics: Chemistry and Pharmacology
    Notes: Summary Two different methods have been used to investigate the retention mechanism of a series of imidazole derivatives in reversed-phase liquid chromatography (RPLC) over a range of column temperatures and with different concentrations of hydroxypropyl-β-cyclodextrin (HP-β-CD) in the mobile phase. The first approach was the separate study of each factor affecting the retention mechanism; the second method was the simultaneous variation of all these factors. Changes in Van't Hoff plots as a function of HP-β-CD concentration were examined. Enthalpy and entropy were determined for two physicochemical processes: (i) solute transfer from the mobile phase to the stationary phase, and (ii) solute complexation by HP-β-CD. These thermodynamic data showed that the mechanism of retention of the solute was dependent on the concentration of HP-β-CD in the mobile phase. For a HP-β-CD concentration,C, greater than to 4 mM, from 28°C to a critical temperature,T *, solute retention was entropy-dominated because of inclusion of the solute in the HP-β-CD cavity. AboveT * retention was enthalpy-dominated, because of interaction of the solute with the RP18 stationary phase. At firstT * increased asC was increased up to a critical value,C **; it the remained relatively constant because of auto-association of the HP-β-CD molecules in the mobile phase. Enthalpy-entropy compensation revealed that HP-β-CD-solute complexation had a greater effect on retention than RP18 stationary phase-solute interaction. This confirms that the main parameter determining retention in RPLC is the distribution of the solute in the mobile phase, and that interactions with the stationary phase play a minor role.
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  • 53
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Non-aqueous reversed-phase liquid chromatography ; Evaporative light-scattering detection ; Octadecyl grafted silica ; Ceramides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper describes the development of a chromatographic system for analysis of commercial ceramides structurally similar to those found in the stratum corneum. The ceramides used in this study contain different amine based (phytosphingosine, sphingosine and dihydrosphingosine) and fatty acids of different chain lengths and with different functional groups (hydroxylated and unsaturated). Non-aqueous reversed-phase (NARP) liquid chromatography with evaporative light-scattering detection (ELSD) were the techniques chosen in accordance with the nature of the ceramides. The eluent strength and the potential selectivity of different organic solvents were investigated. On a C18-bonded silica, the most promising chromatographic conditions employed a gradient from ACN-THF, 95∶5, to ACN-THF-PrOH, 35∶5∶60, in 15 min with a constant concentration of TEA (10 mM) and a stoichiometric amount of formic acid.
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  • 54
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    Chromatographia 49 (1999), S. 281-284 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Glucosinolates ; Rapseed-mustard ; Brassica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple, economical and efficient HPLC method has been developed for the separation and determination of the individual glucosinolates in rapessed and mustard. The method involves single-step extraction of glucosinolates with boiling water and separation of the individual glucosinolates on a Novapack RP-18 column (3.9 mm ×150mm) with 0.2 M ammonium sulphate as mobile phase. Peaks were monitored at 229 nm. All major glucosinolates could be eluted within 10 min. The method proved effective for routine analysis of glucosinolates.
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  • 55
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    Chromatographia 49 (1999), S. 535-538 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solid phase extraction ; Herbicides in soil ; Flupoxam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance liquid chromatography with UV detection was used to determine the residues of flupoxam (a new herbicide) in soils. Soil samples were extracted with aqueous methanol. The soil extracts were cleaned up and concentrated using two solid phase extraction columns: a polymeric stationary phase based on a polystyrene-divinylbenzene resin (Lichrolut EN) and alumina. Recovery experiments were performed at ppb levels in spiked soil samples. The recovery was 76±1.7% for flupoxam in the range 5–100 μg kg−1 of soil. Limit of determination was 3 μg kg−1.
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  • 56
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; α-Chymotrypsin-CSP ; Enzymatic chiral separations ; Loadability evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Several racemates has been resolved according to an enzymatic recognition mechanism on an α-chymotrypsin chiral stationary phase. The loadability of the ACHT-CSP has been evaluated both in buffered and non-buffered mobile phases under the enzymatic process and compared with the loading capacity obtained by the structural recognition process.
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  • 57
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Enantioseparations ; Amylose phenylcarbamate phase ; Glycidyl sulfides ; Glycidyl selenides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The resolution of the enantiomers of a series of glycidyl sulfides and glycidyl selenides has been examined on a chiral stationary phase prepared by coating aminopropylated silica gel with amylose tris-(phenylcarbamate). Most of the enantiomers of glycidyl monosulfides and monoselenides could be resolved satisfactorily but those of the disulfides could not. The effects of solute structure and of the concentration of 2-propanol in the mobile phase on retention and resolution were investigated.
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  • 58
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cis-diamminedichloroplatinum (II) ; Transdiamminedichloroplatinum (II) ; Amminetri-chloroplatinate ; 4-Methyl-2-thiouracil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary We have developed a simple, rapid, selective and sensitive method for detecting the antitumour agent cis-diamminedichloroplatinum (II) (cisplatin) (CDDP) and its toxic impurities trans-diamminedichloroplatinum (II) (transplatin) (TDDP) amminetri-chloroplatinat (ATCP) anion using HPLC in one run. By using 4-methyl-2-thiouracil (MTU) as a derivatizing agent, new compounds have been formed from the Pt compounds and separated on a μ-Bondapak C18 column with isocratic elution and detection at 315 nm. Reactant concentration, methanol content, pH and the reaction time on yield of derivatives were investigated and the optimum conditions for the detection response were defined. The derivatives of each of the three platinum compounds formed in an acetate buffer solution containing 40% (v/v) methanol and 0.9% KCl solution at pH 3.7 and ambient temperature were only stable for one hour.
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  • 59
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    Chromatographia 49 (1999), S. 306-308 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Digoxin and digoxigenin ; Temperature effects ; Pore size effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Increased retention of digoxin has been observed at elevated temperatures on both 10 nm and 30 nm porediamter, RP-18 packing. This result is the opposite effect compared with the decreased retention under the same conditions with digoxin aglycon-digoxigenin. Rotation around the C−C σ-bonds in the digoxin molecule is presumed; the rod-like molecules of the newlyobtained digoxin penetrate stationary phase pores more easily thus increasing retention.
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  • 60
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion chromatography ; Monovalent anions determination ; Potentiometric detection ; Ion selective PVC-matrix electrode
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    Topics: Chemistry and Pharmacology
    Notes: Summary An all solid-state contact tubular PVC-matrix membrane electrode has been applied for potentiometric detection of inorganic and organic monovalent anions using phosphate and hydrogen phosphate eluents at low concentrations. This is a “monovalent detection method” as the selectivity of the electrode towards monovalent anions results in some other anions being undetected unless the concentration of those other anions is higher than 10−3 mol dm−3 in the sample solution injected. It takes only eight minutes to complete the separation with a good resolution. Theoretical and practical considerations are discussed, and in particular, sensitivity, linearity, detection limit and dynamic behaviour are presented. The use of an all solid-state contact bromide-selective electrode as a detector offers so far the best simultaneous sensitivity toward all anions when compared with other detection methods. Determination of Cl− and NO3 − ions in river, rain and drinking water samples without any further sample preconcentration has been successfully achieved. The detection limit is sub-ppb for most of anions in a 20 μL injection volume.
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  • 61
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Evaporative light scatering detection ; APCI mass spectrometry ; Triacylglycerols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Short- and long-chain triacylglycerols (SLCT) are a family of lipids prepared by chemical or enzymatic interesterification of triacetin, tripropionin and/or tributyrin, and long-chain (C16!18) hydrogenated vegetable oils. In this study, a normal-phase cyanopropyl high-performance liquid chromatographic (HPLC) method was developed for the separation and quantification of SLCT. The method is capable of separating SLCT mixtures, free fatty acids and the neutral lipid classes of saturated long-chain triacylglycerols, diacylglycerols and monoacylglycerols. To characterize the specific SLCT classes, a normal-phase HPLC procedure using a non-modified silica column was developed to separate the SLCT into individual isomers based on total carbon number and position of fatty acids on the glycerol backbone. Online coupling with a mass detector (LC/MS) allowed the identification of the individual triacylglycerol structures.
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  • 62
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    Chromatographia 49 (1999), S. 424-430 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Octadecyl titania ; Surface hydrosilation ; Solid-state NMR C7
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    Topics: Chemistry and Pharmacology
    Notes: Summary The structure of a C18 phase based on titania (C18-A), synthesized by the method of solution polymerization, is investigated by diffuse reflectance infrared Fourier transform (DRIFT) and solid-state nuclear magnetic resonance (NMR) spectroscopy. The findings are compared with the results of a second C18 phase based on titania (C18-B) which was synthesized by the method of surface hydrosilation. The dynamic behavior of both phases is examined by1H MAS NMR detection of spinlattice relaxation times in the rotating frame (T1pH) and conventional spin-lattice relaxation times (T1). Due to a smaller ligand density, phase C18-A appears to be a somewhat more mobile than phase C18-B. The chromatographic capability of the phase C18-A is demonstrated by the separation of samples containing benzene derivates or anilines. The elution order is analogous to the phase C18-B, but for both test mixtures the polarity of the mobile phase has to be increased. Phase C18-A is classified as being polymeric by the Sander and Wise test, whereas phase C18-B shows intermediate retention behavior.
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  • 63
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; NMR spectroscopy and mass spectrometry ; Plant products ; Silene otites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary HPLC coupled in parallel to nuclear magnetic resonance (NMR) and mass spectrometry (MS) has been used to obtain1H NMR and mass spectra of a number of ecdysteroids present in an extract of the plantSilene otites. Reversed phase gradient chromatography was performed using a D20-acetonitrile-based solvent system. NMR and mass spectra were obtained for integristerone A, 20-hydroxyecdysone, 2-deoxy-20-hydroxyecdysone and 2-deoxyecdysone to provide structural confirmation using continuous and stopped flow HPLC-NMR. The combined HPLC-NMR-MS system described here provided a more comprehensive analysis of the ecdysteroids present in the extract than HPLC-NMR alone.
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  • 64
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; O-alkyl, O-(1-methylthioethylideneamino) phosphoramidates ; Quantitative structure-retention relationship (QSRR) ; Reversed-phase LC
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    Topics: Chemistry and Pharmacology
    Notes: Summary By using factor analysis, cluster analysis and multiple linear regression methods, two parameters, FHF and ECCR, were selected from eight solute-related structure parameters as showing the best correlation with retention data. The relationship between the retention data (k) and these two structure parameters were established for ten O-alkyl, O-(1-methylthioethylideneamino) phosphoramidate compounds under the experimental conditions studied. Retention data (k) for six other compounds that have a high correlation with structure parameters were predicted using these QSRR equations. The system was evaluated by comparing the experimentalk values with the predicted ones. Good agreement was obtained between the experimental and predictedk values.
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  • 65
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    Chromatographia 47 (1998), S. 25-34 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solid Phase Extraction ; RP-HPLC gradient analysis ; Taxus Cell Cultures ; Taxol and Taxanes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Solid phase extraction (SPE) methods are studied for the sample pretreatment for HPLC analysis ofTaxus cell suspension cultures. Various types of SPE materials were tested for the extraction of both the taxane standards and samples of various origin. Comparison between the different cartridges and the different elution solvents are made in terms of extraction recovery and sample clean-up. Selective elution of the taxanes is achieved by a gradient elution scheme.
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  • 66
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    Chromatographia 47 (1998), S. 77-80 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion chromatography ; Stability constants ; Ionic strength ; Heavy metals ; Tartaric acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Ion chromatography and potentiometry were used for the determination of the stability constants Pb, Zn, Co, Ni, Mn tartrate complexes at different ionic strengths. An extrapolation function based on the Debye-Hückel equation was applied to obtain the thermodynamic stability constants.
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  • 67
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair LC ; Plasma ; 2,4-Toluendiamine ; 2,6-Toluendiamine
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    Topics: Chemistry and Pharmacology
    Notes: Summary An ion-pair HPLC method is presented for the determination in plasma of 2,4- and 2,6-toluendiamine (TDA), known carcinogens. The chromatographic conditions consisted in isocratic elution on a reversed phase C18 column with 5 mM octanesulfonic acid in methanol-water, 45∶55, as mobile phase. UV detection was performed at 235 nm. Samples were analyzed after a simple single step liquid-liquid extraction and the method was validated by measurement of precision (interassay and intraassay), sensitivity, specificity, linearity, and recovery. The detection limit for both TDAs in plasma was 20 ng mL−1. The correlation coefficients based on the intrassay calibration curve were 0.998 and 0.997 for 2,6- and 2,4-TDA, respectively. The intraassay accuracy, expressed in terms of recovery, was found to be up to 89.91% and 97.05% for 2,6- and 2,4-TDA, respectively.
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  • 68
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Enantiomer separation ; Voriconazole (UK-109,496) ; Effect of organic mobile-phase modifier
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    Topics: Chemistry and Pharmacology
    Notes: Summary Coupled achiral-chiral high-performance liquid chromatography (HPLC) with an achiral amino-based column coupled with a chiral amylose-based column has been used for qualitative and quantitative determination of the potential chiral and achiral impurities of Voriconazole (UK-109,496), a new antifungal agent with two stereogenic centres. The effect of the organic mobile-phase modifier, ethanol, was studied. The assay response was linearly dependent on concentration over the range 1.2–40.4 μg for Voriconazole and 2.5–104.0 ng for the impurities. The limit of detection was 2.5 ng for each analyte.
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  • 69
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion chromatography ; Titania packings ; Inorganic anions and cations
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    Topics: Chemistry and Pharmacology
    Notes: Summary The ion-exchange retention behavior of titania synthesized in our laboratory was investigated by ion chromatography of inorganic anions and cations. Dilute acetic acid-sodium acetate and bicine-sodium hydroxide buffers were used as mobile phases with no use of suppresor. We observed that the titania, although poor at separating monovalent anions expcept nitrite ion in this experiment, was both an anion and a cation exchanger, and selectively retained fluoride and carbonate ions. We concluded that because of its specific retention properties there were possibilites of using this amphoteric exchanger for simultaneous analysis of anions and cations, and of using it as a selective packing material for ion chromatography.
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  • 70
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Porous graphitic carbon ; Optimization ; Morphine and metabolites
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    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic behaviour of a series of morphine-based opiates has been investigated using a porous graphitic carbon packing material at acid and alkaline pH. The effects of mobile phase pH, mobile phase organic percentage, column temperature and ionpairing agents were studied. All six opiates were separated within a close retention window despite large differences in measured lipophilicities of the individual opiates. The retention order was not related to the log P values of the opiates and strong retention of the fully ionised compounds was observed, particularly those with acidic functional groups. The effect of pH on the retention of the compounds indicated that the degree of ionisation of the individual compounds was important in the separation mechanism, suggesting that hydrophobic interactions were present in addition to the polar retentive effects observed above. The strong retention of the ionised glucuronide and sulphate conjugates of morphine is a particularly useful feature of the porous graphitic carbon packing material which has general applicability to the analysis of polar or ionised drug metabolites.
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  • 71
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amperometric detection ; Solid-phase extraction ; Plasma ; Clozapine
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    Topics: Chemistry and Pharmacology
    Notes: Summary A sensitive and selective high-performance liquid chromatographic method has been developed for monitoring clozapine levels in human plasma. Chromatography was performed on a reversed-phase column (C8, 150 mm×4.6 mm i.d., 5 μm) with acetonitrile-aqueous sodium acetate solution, 88∶12 (v/v), as mobile phase; the flow rate was 1 mL min−1. Clozapine oxidation at +800 mV was detected amperometrically. Response was linearly dependent on concentration over the range 50–1500 ng mL−1 clozapine in plasma. Sample preparation by solid-phase extraction before HPLC analysis gave high extraction yield (94%). The accuracy and precision of the method were both very good (recovery: 97%;RSD〈3.3%).
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  • 72
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    Chromatographia 47 (1998), S. 299-304 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Plasma samples ; Direct injection ; Restricted-access media ; Column-switching
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    Topics: Chemistry and Pharmacology
    Notes: Summary A new restricted access media (RAM) type of precolumn, Bio Trap 500 C18, for direct injection of plasma samples in column-switching systems was evaluated with respect to the elution of plasma proteins in different mobile phases, the loading capacity of plasma samples, the chromatographic behavior during plasma injections and protein contamination of the packing and sealings. More than 95% of plasma proteins could be excluded from the precolumn within three minutes for all selected mobile phases. Quantitative analyte recoveries could be obtained by injecting plasma samples ranging from 5 to 500 μL with the analyte mass〉150 ng onto a BioTrap 500 C18 column (20×4 mm I.D.). One precolumn tolerated about 15 mL of plasma injection without out noticeable change in retention and pressure. Clogging of the precolumn was encountered (≥45 mL of plasma) due mainly to the adsorption of proteins on the packing. The performance of the analytical column (Kromasil C18) was also examined. The column efficiency decreased by 60% after processing 45 mL plasma in total.
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  • 73
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    Chromatographia 47 (1998), S. 373-382 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polyaromatic hydrocarbons ; Pitch
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    Topics: Chemistry and Pharmacology
    Notes: Summary A new high performance liquid chromatography method for the characterisation of toluene-soluble fractions of pitches has been developed. Although a chromatographic system typical of size exclusion chromatography was used, results indicate that, for these structurally complex samples, separation does not follow the usual discrimination by molecular size. A differentiation between several classes of polyaromatic hydrocarbons is achieved instead. Data are reported on the analysis of individual standard polyaromatic hydrocarbons, showing that four different elution ranges can be observed: three ofcata-condensed compounds (Cata1, Cata2 and Cata3) and one ofperi-condensed compounds (Peri). Results are reported proving the capacity of this high performance liquid chromatography method to distinguish between pitches of different origin and nature. It is also effective for the study of the chemical reactions occurring during heat treatment.
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  • 74
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Opium alkaloids ; Papaver somniferum L.
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    Topics: Chemistry and Pharmacology
    Notes: Summary A reversed phase HPLC method for the separation of the five major alkaloids fromPapaver somniferum L., morphine, codeine, thebaine, papaverine and noscapine, has been developed and validated. By use of a basedeactivated silica-based stationary phase excellent peak shape was achieved for each substance. The five alkaloids were quantified by internal standardization within 20 min and with good precision. The method is applicable to opium and to poppy straw.
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  • 75
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Carbofuran pesticides ; On-line analysis of milk
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    Topics: Chemistry and Pharmacology
    Notes: Summary A method has been developed for extraction and determination of carbofuran in milk. The method involved direct injection of raw milk on to a human serum albumin dimethyloctyl-silica gel (HSA-C8) column and the use of 80:20 (v/v) 0.01 M phosphate buffer pH 5.5-acetonitrile as mobile phase. UV spectrophotometric detection was performed at 220 nm. Identification was based on retention time. Quantification was performed by automatic peak-area determination and was calibrated by use of an external standard.
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  • 76
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    Chromatographia 48 (1998), S. 17-19 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Dibromomannitol in plasma ; Pharmacokinetics
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    Topics: Chemistry and Pharmacology
    Notes: Summary Myelobromol 1,6-dibromo-1,6-dideoxy-D-mannitol (dibromomannitol, DBM) is a bifunctional alkylating agent that has been in clinical use since 1963. It is currently included at high dose in preconditioning regimen for bone marrow transplantation (BMT) and is a main-stay of treatment for polycythaemia vera. A high-performance liquid chromatographic method was developed for the determination of DBM in the plasma. The basis of the assay is a derivatization with sodium-diethyldithiocarbamate at 42°C in the presence of 1-bromo-1-deoxy-3,6-anhydro-galactitol as internal standard (IS). The analysis was carried out on a 250×4mm Hypersil 5 CPS column equipped with a 20×4 mm Hypersil 10 CPS precolumn. The eluent consisted of heptane:isopropyl-alcohol: glacial acetic acid=600:76:80 w/w. The flow rate was 1.2 mL min−1. UV detection was performed at 254 nm. The calibration graph was linear in the concentration range of 2.5–260 μM of DBM in plasma. The limit of detection was 1.0 μM. The precision and accuracy of the method was between the good laboratory practice (GLP) required limits.
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    Chromatographia 48 (1998), S. 37-42 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Biologically active amines ; Polyamines ; Cereal and Cereal products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Biologically active amines (putreanine sulphate, N-acetyl putrescine, putrescine, cadaverine, histamine, agmatine, N-acetyl spermidine, spermidine, spermine) were separated and quantified in cereal flour and cereal products by a liquid chromatographic method. The method consists of the separation of ion pairs formed between biologically active amines and octanesulphonic acid on a reversed-phase column, postcolumn derivatization with o-phtalaldehyde-2-mercapthoethanol and spectrofluorometric detection. Results of the reliability study were satisfactory. The method was linear for each amine at 1–10 mg L−1. Putrescine and spermidine were the only amines always detected in cereal flour and cereal products, ranging from 2.45 to 47.83 mg kg−1 for putrescine and 3.27 to 37.14 mg kg−1 for spermidine. The most important differences among types of samples were found in polyamine derivatives.
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  • 78
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Normal- and reversed-phase LC ; Fumagillin in fish samples
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    Topics: Chemistry and Pharmacology
    Notes: Summary Fumagillin is an antibiotic agent mostly used in the veterinary profession. A normal-phase liquid chromatographic method was developed for the determination of this drug in fish matrices. A hexane-dichloromethanedioxan-2-PrOH-acetic acid (43:43:9:5:0.1 v/v %) eluent was used on a Perkin Elmer silica gel column. For validation of the process a reversed-phase HPLC method was also developed (eluent: acetonitrile-water-bicyclohyxylamine 70:30:0.05 v/v %, with Spherisorb ODS, as stationary phase). Recovery is about 100% and the limit of detection is 5 ng g−1 for meat samples.
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  • 79
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Buckminsterfullerene ; Hydrogenation ; Separation technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of composition and flow rate of the mobile phase on the HPLC separation of hydrogenated buckminsterfullerene (C60Hn n=2–38) was investigated on BuckySep column. Toluene was used as the basic solvent and hexane, heptane, cyclohexane, THF, acetonitrile, acetone, ethanol and 2-propanol as co-solvents. The fraction of co-solvents was varied 10–80%, and the flow rate 1–0.1 mL min−1. Toluene-acetonitrile 65∶35 and toluene-acetone 50∶50 provided the best separation. Under the best conditions complete separation of C60H2 and almost complete separation of the four most abundant isomers of C60H4 were achieved. Separation of derivatives with higher hydrogen content was very poor.
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    Chromatographia 47 (1998), S. 440-442 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Preparative scale separations ; Chiral stationary phase ; Enantiomer separation ; Morphanthridine analog
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparative chromatographic enantioseparation of a chiral morphoanthridine analog has been performed on an analytical column using amylose-tris(3,5-dimethylphenylcarbamate) as chiral stationary phase. The racemate (100 mg) was resolved to baseline within 15 min. This paper describes the development of the method, estimation of the capacity of the chiral stationary phase and discussed the potential of the chromatography if performed under preparative conditions. From the results and calculations presented it seems likely that the resolution of 70 tons year−1 could easily be achieved on 30 kg of stationary phase with a mobile-phase consumption of only 720 L day−1.
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  • 81
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    Chromatographia 47 (1998), S. 449-450 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chitin stationary phase ; Marrubiin ; Analgesic activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Marrubiin is the main active compound isolated fromM. vulgare, a medicinal plant used in folk medicine to cure several diseases. The present study shows that chitin, an abundant natural polymer, may be successfully in chromatography column to separate marrubiin from complex mixtures. The experimental procedure described here represents an efficient and rapid method to obtain such compound in high yield.
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  • 82
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Affinity chromatography ; Molecular imprinting ; Molecular recognition ; Combinatorial libraries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Molecular imprinting is an attractive method for producing highly selective adsorbents, and several new and potentially useful applications based on molecularly imprinted polymers (MIPs) have been described in recent years. In this article, we highlight some of the areas where these materials have found application, and also describe some new fields of application where the selectivities of imprinted materials can be gainfully employed, for example as binding matrices in the screening of combinatorial libraries, and as auxiliary agents in enzymatic syntheses.
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  • 83
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fermentation ; Microdialysis sampling ; Monosaccharides and ethanol ; On-line monitoring ; Biosensors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two amperometric biosensors were used as detection units in liquid chromatography for on-line monitoring of the production of fuel ethanol during a fermentation. Sampling was performed with a microdialysis probe, and the dialysate was introduced into a liquid chromatographic system providing separation of the substrates and the product: three monosaccharides and ethanol. The analytes were detected by two carbon paste electrodes based on pyranose oxidase and alcohol oxidase, respectively, co-immobilised with horseradish peroxidase, operating in parallel at −50 mVvs. Ag/AgCl. The measured linear ranges of the biosensors by direct injection into the LC system were for glucose 0.3–2.5 g L−1, xylose 0.5–6.7 g L−1, galactose 0.5–6.7 g L−1, and ethanol 1.6–11.7 g L−1, respectively. Injection of standard solutions were required to monitor the stability of the biosensors. Due to the strict selectivity of the biosensors, no interference from other compounds in the broth was encountered from other compounds in the broth was encountered in the quantification. The fermentation process was monitored for 16 h. The on-line results were compared with off-line measurements.
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  • 84
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cisapride in plasma ; Pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An HPLC method has been developed for the quantification of cisapride in plasma for pharmacokinetic studies. Clebopride was used as internal standard. Plasma samples were extracted at alkaline pH withtert-butyl methyl ether. The organic phase was then extracted with sulphuric acid to eliminate endogenous interferences, and cisapride and the internal standard were then extracted at alkaline pH intotert-butyl methyl ether. After evaporation oftert-butyl methyl ether, the residue was analysed by HPLC. Chromatography was performed at 20°C on a 250mm×4mm i.d. reversed-phase column selective for basic compounds. The isocratic mobile phase was 48∶52 (v/v) acetonitrile-water containing 0.05 M potassium dihydrogen phosphate and 0.04 M triethylamine, adjusted to pH 5.5; the flow rate was 1 mL min−1. Cisapride and the internal standard were detected by ultraviolet monitoring at 276 nm. The calibration graph was linear for quantities of cisapride from 1 to 200 ng mL−1. Intra- and inter-day precision (CV) did not exceed 13.98%. The limit of quantitation (LOQ) was 0.68 ng mL−1 for human plasma. The applicability of the method has been demonstrated in a pharmacokinetic study of normal volunteers who received 10 mg cisapride orally.
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  • 85
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    Chromatographia 47 (1998), S. 285-290 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Enantiomeric separation ; β-Cyclodextrins ; Methylenedioxylated amphetamines ; Ecstasy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Native and derivatized β-cyclodextrins such as chiral stationary phases (CSP) were used for the simultaneous enantiomeric separation of four methylenedioxylated amphetamines (MDA, MDMA, MDEA and MBDB) by liquid chromatography. Fluorimetric detection was used in order to enhance sensitivity and selectivity. The mobile phase was, optimised by studying the influence of pH, triethylamine concentration, organic solvent type, column temperature and flow rate of the mobile phase. This method was validated by determining linearity, precision, accuracy, limits of detection and quantification, and was applied to the stereoselective analysis of illicit tablets (23 samples) and of human whole blood samples (spiked samples and two post-mortem cases). Whereas no significant deviation from a racemic ratio was observed in the tablets contents, the analysis of blood samples showed an enantioselective metabolism of MDMA.
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  • 86
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Aminopropyl-silica sorbent ; Continuous cleanup/preconcentration ; Hydroxyvitamin D3 metabolites ; Flow injection analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new procedure for continuous cleanup and concentration of hydroxyvitamin D3 metabolites prior to their separation by HPLC and UV-detection is reported. The process is based on the use of aminopropyl-silica as solid-phase sorbent as an alternative to the use of nonpolar sorbents. The improvement thus achieved has been tested by comparing the results with those obtained using octadecyl-C18 as non-polar sorbent. The comparison has been based on the calibration graphs (linear range, detection and quantitation limits), precision and multiple standard addition method.
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  • 87
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Coulometric detection ; Mandelic acids ; Phenylglycols ; Urine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method has been developed for the quantification of urinary 3,4-dihydroxymandelic acid (DOMA), 4-hydroxy-3-methoxymandelic acid (VMA), 3,4-dihydroxyphenylglycol (DHPG), and 4-hydroxy-3-methoxyphenyglycol (MHPG). Separation and determination of these compounds in biological samples was previously thought to be very difficult. In this work the separation has been achieved by reversed-phase high-performance liquid chromatography with step-wise gradient elution with three mobile phases. The conditions for coulometric detection have been optimized for effective determination of these compounds. In analysis of a sample of human urine, after a simple deproteinization proceudre, DOMA, VMA, DHPG, and MHPG were separated from interferences and quantified successfully; the average levels of these compounds in six different samples were 33.87±1.03, 1202±41.3, 31.3±1.92, and 80.6±2.15 μg (24 h)−1, respectively. Their precursors E, MN, DOPA, DA, NE, DOPAC, HVA, 3MT, and NMN, and the indolamine 5HT and its metabolite 5HIAA (a list of abbreviations is given at the end of the paper) can also be determined simultaneously in the same chromatographic run. The overlapping peak of DHPG was resolved by deconvolution.
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  • 88
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Optimization ; Mixture design ; Special cubic polynomial model ; Pareto-optimality ; Overlapping resolution mapping (ORM)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A systematic approach, using a mixture-design statistical technique, has been developed for selecting the optimum mobile phase for the separation of fat-soluble vitamins in reversed-phase high-performance liquid chromatography. A quaternary mixture of methanol, acetonitrile, tetrahydrofuran and water was used as mobile phase. Retention time and peak width were recorded in ten runs augmented with five replicates and the data were subsequently fitted to special cubic polynomial models. The resulting mathematical equations enabled prediction of resolution over the entire parameter space. Contour plots of minimum effective resolution and maximum retention time as a function of mobile phase composition are presented and discussed. Visual inspection of these plots provides an overview of the quality of the separation and the analysis time required for each possible mobile-phase composition with n the parameter space. It is demonstrated that the methodology followed was an important tool which enabled the taking of informed decisions necessary for selection of the optimum mobile phase for a chromatographic separation. A combination ofR S minimum andt R maximum as optimization criteria in a multicriteria decision-making plot using pareto-optimality concept is discussed. This combination enabled visual demonstration of the compromise between separation quality and the economics of analysis time. Our methodology has been compared with the common used technique of ‘overlapping resolution mapping’.
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  • 89
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    Chromatographia 47 (1998), S. 457-464 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Imprinted polymer ; Non-covalent imprinting ; Selectivity and capacity ; Association constant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Imprinted polymers as stationary phases for HPLC separations have been the subject of extensive investigations in recent years. In order to aid the rational design of synthetic protocols for the preparation of imprinted polymers, a series of calculations were made to assess the equilibrium concentration of templatemonomer complexes as a function of association constant (K) for the functional groups involved in the interactions and initial concentrations of reactants. This data was then used to predict the selectivity of polymers prepared under different reaction conditions and the model was tested using an experimentally determined value ofK and separation factors taken from the literature.
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  • 90
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; N-(dansyl)-dl-amino acids ; Human serum albumin ; Chiral discrimination ; Optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of perchlorate anion as mobile phase modifier on the separation factor, α, forN-(dansyl)-dl-norvaline andN-(dansyl)-dl-tryptophan on a human serum albumin (HSA) column was studied by varying the concentration,c, of the chaotropic agent and the column temperatureT. Gibbs-Helmholtz parameters Δ(ΔH) and Δ(ΔS) between thed andl enantiomers were determined from linear van't Hoff plots of lnα against 1/T. Thermodynamic results indicated that the enhancement of the separation factor observed asc was increased was enthalpically controlled owing to stereoselective H-bonding interactions. Such behavior was used to optimize the chromatographic conditions for separation ofN-(dansyl)-amino acids on HSA.
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  • 91
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solid phase extraction ; Sample treatment optimisation ; Taguchi method ; Albendazole metabolites ; Milk samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed phase HPLC methods for the determination of two metabolites of albendazole in cow's milk are described. Albendazole is an anthelmintic agent used both in veterinary and human practice. Its main metabolites are albendazole-sulfoxide and albendazole-sulfone. The separation of the two metabolites was performed on a μ-Bondapak C-18 column using an acetonitrile/methanol/phosphate buffer as mobile phase, with detection at 290 nm. For the sample preparation of the milk samples we used solid phase extraction. A new sample treatment optimisation procedure is also presented for the sample preparation method. Since sample preparation is a critical step in the analysis of residues in biological samples, the second part of our publication describes an optimisation using Taguchi's methodology that increased recovery, accuracy and reliability. After optimisation of the sample preparation, the limit of detection was 10 ng mL−1 milk and the recovery was 70–80% in the concentration range of 30–1000 ng mL−1 milk for both metabolities.
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  • 92
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ketotifen analysis ; Stability indicating analysis ; Aqueous and oil-based formulations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and specific high-performance liquid chromatographic (HPLC) method for the analysis of ketotifen in aqueous solutions and silicon oil suspensions is described. The HPLC system is based on a reversed phase μBondapak C18 (30×0.39 cm) column with a mobile phase of phosphate buffer (0.001 M, pH 7.4):methanol: acetonitrile: trimethylamine (29.8:45:25:0.2, by volume) at a flow-rate of 1 mL min−1. The eluent was monitored by UV absorption at 299 nm. Silicon oil-based samples were extracted with HCl (0.05 M) using imipramine as internal standard. The recovery of ketotifen and imipramine was greater than 80%. The calibration curves for both assays were linear over the ranges examined, yielding correlation coefficients greater than 0.997. The assay was shown to be stability indicating by subjecting solutions of ketotifen in phosphate buffer to heat, oxidative stress and irradiation with ultraviolet light (254 and 369 nm)for up to 8 h. The methodology was also shown to be applicable for the analysis of ketotifen in simple aqueous based formulations, in suspension in silicon oil and for the analysis of samples derived fromin vitro skin transfer experiments.
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  • 93
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    Chromatographia 48 (1998), S. 43-47 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Vitamin C analysis ; Ascorbate-2-phosphate and sulphate esters ; Enzyme shifting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method was devised to assay four forms of vitamin C: L-ascorbic acid (AA), dehydroascorbic acid (DHA), ascorbate-2-mono- and polyphosphate (AMP, APP), as well as ascorbate-2-monosulphate (AMS), in sample series of different fish tissues and feed. Direct and indirect detection were combined. Sample extractions were carried out with 0.2 mol L−1 sodium acetate buffer (pH 4.8) and extracts were deproteinized after different chemical or enzymatic reactions, with perchloric acid. The DHA was reduced to AA with dithioerythritol (DTE). Ascorbate oxidase enzyme was used for the detection of background and an acidic phosphatase enzyme for the hydrolysis of different phosphate esters. Ascorbate-2-sulphate was detected directly with help of coinjection of the compound. Chromatographic analysis was carried out with a single column isocratic reverse phase method. The mobile phase was an aqueous buffer of 0.04 M sodium-acetate, 0.05 mM EDTA, 0.5 mM tetrabutylammonium dihydrogen phosphate (TBA) adjusted to pH 3.76 with 85% H3PO4 and with 24 mL methanol added to 1000 mL. C-18 columns were used with 0.6 mL min−1 flow rate at 23°C. The vitamin C forms were detected by UV absorption at 250 nm. The determination limit was 1.0–5.0 μg g−1 in AA equivalent. The standard deviations were between 1–6% and depended on the concentrations of vitamin C forms and tissues. Recoveries were between 90–96% in samples.
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  • 94
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Multicomponent mixtures ; Separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Coupling of full adsorption-desorption and size-exclusion chromatography (FAD-SEC) has been applied to the separation and molecular characterization of three- and four-component polymer blends. The method is based on the full adsorption of alln orn−1 components of the polymer blend in a specially designed FAD minicolumn. By appropriate eluent switching the adsorbed polymers are desorbed stepwise from the FAD minicolumn into an on-line SEC column for molecular characterization. It is shown that the desorption isotherms of particular blend components give valuable information about the appropriate displacer composition. The exact position of the desorption isotherms depends, however, both on the amount of polymer adsorbed and in the presence of other, chemically different, polymers within FAD column. The nature and composition of the displacer must, therfore, be adjusted if the intervals between the desorption of particular blend components are to be large enough to prevent displacement overlap.
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  • 95
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    Chromatographia 48 (1998), S. 360-364 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Acylated anthocyanins ; Rudbeckia hirta L. ; In vitro cultures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Conditions were determined for the separation of a complex set of anthocyanins (free aglycones, mono- and multiglycosides and esterified forms) by HPLC. The optimised gradient elution method was then used to carry out qualitative and quantitative analysis of anthocyanin compounds present in the callus tissue ofRudbeckia hirta L. and the tubular flowers of the soil-based plant. The summary content of anthocyanin pigments and the content of the main pigment was identified in the analysed biomass. The method developed is useful for the purposes of monitoring the process of biosynthesis of anthocyanins in tissues obtained through in vitro cultures. The advantages of the method for anthocyanins and its application to other anthocyanin-rich materials are also discussed.
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  • 96
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Basic drug compounds ; Amino additives ; Cyanoalkyl columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of basic antidepressant and antipsychotic drugs on a cyanoalkyl-bonded silica column has been studied to determine the effects on peak retention, symmetry, efficiency, and resolution of six different amine mobile-phase additives. The amines—ammonia,n-butylamine, triethylamine,N,N-diisopropylethylamine,N,N-dimethylbutylamine andN,N-dimethyloctylamine—were, except forN,N-diisopropylethylamine, chosen because of their widespread use for improvement of peak symmetry in chromatographic methods;N,N-diisopropylethylamine was included as an example of a sterically hindered amine to see if the stereochemistry around the nitrogen atom is an important consideration in the selection of an additive. This study shows that a gain in symmetry and efficiency is accompanied by loss of resolution. The results obtained also indicate that one type of amine additive should be used when symmetry and efficiency are most important and another when resolution is paramount.
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  • 97
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amphotericin B ; Oil-water lecithin-based microemulsions ; Extraction of drug from microemulsion ; Reversed-phase HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method employing extraction then reproducible reversed-phase high-performance liquid chromatography (RPHPLC) with monitoring of the drug by absorbance at 405 nm has been developed and validated for the determination of amphotericin B in oil-water lecithin-based microemulsions. The precision and accuracy of the method are excellent (SD 2.4% and 4.2%, respectively). The established linearity range was 10–60 μg mL−1 (r 2=0.9967). The recovery of amphotericin B from spiked placebo was 〉90% over the linear range. The extraction procedure was simple and the HPLC conditions were able to separate the drug from its degradation products and excipients. The method has been used successfully for determining the amphotericin B content of microemulsions and for evaluating the chemical stability of amphotericin B-loaded microemulsions.
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  • 98
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    Chromatographia 48 (1998), S. 183-189 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polymeric phases ; Shape selectivity ; PAH selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Stationary phases with octadecyl groups have been prepared with different carbon content without and in the presence of water and characterized for their selectivity for the shape of various polyaromatic hydrocarbons. It is shown that both a high hydrocarbon content and a good accessibility of the bonded groups within the pores is required to achieve shape recognition for PAH. High carbon content alone is not sufficient. The two tests for shape selectivity proposed by Sander and Wise as well as by Tanaka are compared. In most cases the results are similar: A low selectivity with the Sander and Wise test (α TBN/BaP〈1) corresponds to a high value with the Tanaka test (α TRI/o-TER〉3). However, not in all cases the tests give corresponding answers. Further studies on molecular recognition are required.
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  • 99
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    Chromatographia 48 (1998), S. 197-202 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Molecular imprinting ; Molecular recognition ; Chiral recognition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Molecularly imprinted polymers were prepared using 2-vinylpyridine and/or methacrylic acid as functional monomers in a self-assembly imprinting protocol. The resulting polymers were analyzed in aqueous media, and the effects from the pH of the mobile phase and the degree of added organic solvent were investigated. The results are indicative of the importance of ionic bonds in conjunction with hydrophobic interactions in the formation of the complexes between the analyte and the polymers.
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  • 100
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    Chromatographia 48 (1998), S. 190-196 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-interaction chromatography ; Dye-coated reversed phase ; Retention model ; Experimental design
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of inorganic anions (NO3 −, NO2 −, Cl−, Br−, I−, SO4 2−, S2O3 2−) by ion-interaction chromatography mediated with a specific dye has been investigated. Chromatography was performed on a LiChrospher RP-18 colum dynamically coated with crystal violet, using acetonitrile-water buffered with phthalate as the mobile phase. The presence of the dye in the eluent enabled indirect spectrophotometric detection of the analytes, which have no significant UV absorption. Retention data were collected for the different anions by varying the composition of the mobile phase according to a full factorial experimental design. A theoretical model for the retention of singly- and doubly-charged analytes, on the basis of the two main processes of ion-exchange and ion-pair formation, has been proposed and validated with the experimental data.
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