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  • Chemistry and Pharmacology  (161)
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  • Articles  (165)
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  • Springer  (165)
  • American Geophysical Union
  • American Physical Society
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  • Chemistry and Pharmacology  (161)
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  • 1
    Electronic Resource
    Electronic Resource
    Encoding of plant odours by receptor neurons in the pine weevil (Hylobius abietis) studied by linked gas chromatography-electrophysiology (1996)
    Springer
    Journal of comparative physiology 179 (1996), S. 331-344 
    Details
    ISSN: 1432-1351
    Keywords: Hylobius abietis ; Olfaction ; Plant odours ; Receptor neuron responses ; Gas chromatography ; Electrophysiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Receptor neuron responses to plant volatiles, trapped by head-space procedures, were examined in the pine weevil Hylobius abietis, using gas chromatography linked with electrophysiological recordings from single neurons. Seventy-two receptor neurons were tested 173 times for various plant volatile mixtures, either via a polar or a non-polar column. 1) All responses appeared as increased firing rates which followed the concentration profiles of the GC-eluted compounds. 2) The neurons were classified separately for the two column types in 17 and 19 groups respectively, according to the compounds they responded to. It suggests that the plant odour information is encoded by a large, but limited number of receptor neuron types. 3) Most neurons responded to a limited number of compounds (1–5) and showed a marked best response to one of them, whereas additional responses to several other components which seems to be structurally similar, was recorded for some neurons. It suggests that the plant odour receptor neurons are rather narrowly than broadly tuned, and that each neuron is specialized for receiving information about one or a few related compounds. 4) Most neurons responded to monoterpenes, whereas the other neurons responded to compounds of other categories. 5) Both major and minor plant volatile components activated specifically receptor neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194987
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  • 2
    Electronic Resource
    Electronic Resource
    The isoprostanes: Unique bioactive products of lipid peroxidation (1998)
    Springer
    Journal of biomedical science 5 (1998), S. 415-420 
    Details
    ISSN: 1423-0127
    Keywords: Isoprostanes ; Oxidative stress ; Lipid peroxidation ; Gas chromatography ; Mass spectrometry ; Human disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The development of a specific, reliable and noninvasive method for measuring oxidative stress in humans is essential for establishing the role of free radicals in human diseases. Currently, accurate techniques to assess oxidant injury in vivo are extremely limited although a number of approaches are being investigated. Of these, the measurement of specific products of nonenzymatic lipid peroxidation, the F2-isoprostanes (F2-IsoPs), appears to be a more accurate marker of oxidative stress in vivo in humans than other available methods. The purpose of this brief review is to acquaint the reader with the IsoPs from a biochemical perspective and to provide information regarding the utility of quantifying these compounds as indicators of oxidant stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02255929
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  • 3
    Electronic Resource
    Electronic Resource
    Adrenal tissue in the male African catfish, Clarias gariepinus: localization and steroid hormone secretion (1995)
    Springer
    Cell & tissue research 280 (1995), S. 653-657 
    Details
    ISSN: 1432-0878
    Keywords: Adrenals ; Morphology ; Steroids ; Gas chromatography ; Mass spectrometry ; Clarias gariepinus (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Interrenal-like tissue in male African catfish is localized in paired organs, situated retroperitoneally anterior of the kidney. Histological and enzyme-histochemical (3β-hydroxysteroid dehydrogenase) reactions were carried out on sections of these organs in order to localize steroid-producing cells. In vitro incubations were carried out to determine the steroidogenic capacity of the interrenal-like tissue. Twenty-one steroids could be identified and quantified in the incubation medium, by means of gas chromatography followed by mass spectrometry. Cortisol, 5α-and 5β-androstanedione and androstenedione together comprised about 80% of the total steroid content. In a previous study, twenty testicular steroids were detected in plasma after castration. In the present investigation we have shown that most of these steroids can be produced by the interrenal-like tissue, which thus can be considered as an extra-testicular source of gonadal steroids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318367
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  • 4
    Electronic Resource
    Electronic Resource
    Adrenal tissue in the male African catfish, Clarias gariepinus: localization and steroid hormone secretion (1995)
    Springer
    Cell & tissue research 280 (1995), S. 653-657 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Adrenals ; Morphology ; Steroids ; Gas chromatography ; Mass spectrometry ; Clarias gariepinus (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Interrenal-like tissue in male African catfish is localized in paired organs, situated retroperitoneally anterior of the kidney. Histological and enzyme-histochemical (3β-hydroxysteroid dehydrogenase) reactions were carried out on sections of these organs in order to localize steroid-producing cells. In vitro incubations were carried out to determine the steroidogenic capacity of the interrenal-like tissue. Twenty-one steroids could be identified and quantified in the incubation medium, by means of gas chromatography followed by mass spectrometry. Cortisol, 5α- and 5β-androstanedione and androstenedione together comprised about 80% of the total steroid content. In a previous study, twenty testicular steroids were detected in plasma after castration. In the present investigation we have shown that most of these steroids can be produced by the interrenal-like tissue, which thus can be considered as an extra-testicular source of gonadal steroids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318367
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  • 5
    Electronic Resource
    Electronic Resource
    Correlations between gas chromatographic retention data of polycyclic aromatic hydrocarbons and several molecular descriptors (1995)
    Springer
    Chromatographia 40 (1995), S. 532-538 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention-structure correlation ; Molecular descriptors ; Polycyclic aromatics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Statistical and factor analysis have been used to test the ability of several molecular descriptors to predict the retention indexes (I) of polycyclic aromatic hydrocarbons determined on SPB-5 and SPB-20 stationary phases. Regression analysis with both columns showed that linear regression with connectivity index and bending energy of the molecules as independent variables gave the best correlation coefficients. ΔI 20–5, considered to be a measure of the polar forces in retention, gave a good correlation with the van der Waals radii of the molecules, or strain, and bending energy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290264
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  • 6
    Electronic Resource
    Electronic Resource
    Relations between pneumatic parameters of ideal gas in a column with uniform permeability (1995)
    Springer
    Chromatographia 41 (1995), S. 15-22 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Average velocity of carrier gas ; Compressibility of carrier gas ; Pneumatic parameters of carrier gas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This report was conceived as a source for the relations between five pneumatic parameters of carrier gas-inlet and outlet pressure, inlet and outlet velocity, and average velocity. Any pair of these parameters can be independent while the remaining three can be expressed as functions of the independent pair. As the total number of the independent pairs is ten, thirty different functions describing relations between arbitrary independent pairs and dependent parameters can be identified. All thirty were derived below together with the complete set of bounds for variations of independent parameters. To derive some relations, a third order rational equation had to be solved. Some properties of that solution are discussed. A simple case of vacuum operations with zero outlet pressure has also been considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274189
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  • 7
    Electronic Resource
    Electronic Resource
    Simulation of column efficiency in temperature programmed gas-liquid chromatography (1995)
    Springer
    Chromatographia 41 (1995), S. 37-42 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Temperature programming ; Isothermal measurements ; Column efficiency ; Dead time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary If the dependence of HETP on temperature is specified under isothermal conditions, it is possible to predict the HETP for programmed temperature elution and subsequently peak width at half-height. This requires knowledge of isothermal retention time at retention temperature, which is computed by means of a model including the variation with temperature of dead time estimated from 3 homologs with carbon number: n, (n+j), (n+jk), where n, j and k are any integers. Predicted and measured peak widths corresponded within 4–9%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274193
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  • 8
    Electronic Resource
    Electronic Resource
    Solid phase microextraction using fused silica fibers coated with graphitized carbon black (1995)
    Springer
    Chromatographia 41 (1995), S. 678-684 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid phase micro extraction ; Graphitized carbon black ; Volatile organic compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper presents the results obtained using fused-silica fibers coated with graphitized carbon black (Carbograph-Alltech) for solid-phase microextraction (SPME). The extraction and calibration curves relative to organic micro-pollutants present in gaseous and aqueous samples are reported. Examples of applications of this extraction procedure to GC and GC-MS analysis of organic micro-pollutants in actual samples are also reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267804
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  • 9
    Electronic Resource
    Electronic Resource
    Preparation and gas chromatographic characterisation of 3-bromo-4-(4-methylbenzyloxy)azobenzene stationary phase (1995)
    Springer
    Chromatographia 41 (1995), S. 697-701 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; New stationary phase ; Packed columns ; Specific retention volumes ; Activity coefficients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The synthesis of 3-bromo-4-(4-methylbenzyloxy)azobenzene (BMBOA) and its use as a stationary phase in packed columns are described. Chromatographic characteristics such as column efficiency, polarity (McReynolds constants) and operating temperature range were studied. Retention factors, specific retention volumes and activity coefficients for alcohols, esters, ketones, aromatic hydrocarbons andn-alkanes were determined. Phenols and 2,3, and 4-chlorobenzyl chlorides were separated on the new phase. Based on experimental data some assumptions were made on the possible types of intermolecular forces between solute and solvent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267807
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  • 10
    Electronic Resource
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    Utilization of Rohrschneider's concept and Tekler equation in linear temperature programmed GC. Precalculation of retention data (1995)
    Springer
    Chromatographia 40 (1995), S. 28-32 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Linear temperature programming ; Tekler-equation extension ; Retention index precalculation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An extension of Rohrschneider's concept to the field of the linear temperature programmed gas liquid chromatography, is proposed, which is based on Antoine's equation for the temperature dependence of the reduction index of Takács et al. and Tekler. The new method presented in this paper, applied to retention data of two stationary phases of low polarity, PS-255 and OV-105, gives a new possibility of precalculating retention data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274603
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  • 11
    Electronic Resource
    Electronic Resource
    Analysis of short chain fatty acids from different intestinal samples by capillary gas chromatography (1995)
    Springer
    Chromatographia 40 (1995), S. 550-556 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Open tubular columns ; Short chain fatty acids ; Intestinal fluids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A capillary gas-liquid chromatography method for the analysis of free short chain fatty acids in intestinal samples was developed. Analytical results obtained with intestinal samples are influenced not only by high molecular mass matrix constituents but also by matrix components with a molecular weight smaller than 5000 daltons. To achieve a faithful transfer of SCFA into the chromatographic system it was important to avoid accumulation of involatile deposits on the surface of the inlet liner. Cleaning of the inlet linear lead to a significant weakening of matrix effects. The method described, using an Innowax column, is more effective, particularly with respect to precision and sensitivity, and is clearly superior to packed columns. The capillary is the column of choice for the separation of short fatty acids in samples from the small intestine and stomach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290267
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  • 12
    Electronic Resource
    Electronic Resource
    The correlation equations describing retention index data on OV-101, OV-275 and PEG 20M.n-Alkanes andn-alkynes (1995)
    Springer
    Chromatographia 41 (1995), S. 726-727 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention indices ; Correlation equations ; n-Alkenes ; n-Alkynes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The correlation equations between Kovats retention indices ofn-alkenes andn-alkynes, column temperature and number of carbon atoms in molecules of these compounds on OV-101, OV-225 and PEG 20M capillary columns have been calculated. The two variable equationI=A+B·n+C/T give a good fit and are the simplest for prctical use.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267812
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  • 13
    Electronic Resource
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    Chromatographic determination of phosphine (PH3) and hydrogen sulfide (H2S) in the headspace of anaerobic bacterial enrichments using flame photometric detection (1995)
    Springer
    Chromatographia 40 (1995), S. 399-403 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Phosphine ; Flame photometric detection ; Anaerobic bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A gas chromatographic method is presented which distinguishes phosphine from hydrogen sulfide and other possible headspace gases of anaerobic microbial cultures. In anaerobic cultures spiked with phosphine, this gas is recovered in the liquid and gaseous phase down to 10 pg per ml of gas or liquid. No biogenically produced phosphine was found. Phosphine in amounts as small as 30 ng per 1 can be stored for several days in glass bottles covered with rubber septa, filled with nitrogen, in the presence or absence of water or of an anaerobic bacterial culture. Due to the selectivity of the detector and the retention characteristics of the porous layer open tubular polymer column alkanes, alkenes and organosulfur compounds routinely found in anaerobic bacterial headspaces do not interfere with the analytical quantification of phosphine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269902
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  • 14
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    Investigation of thermal and analytical properties of two nematic liquid crystals by gas chromatography (1995)
    Springer
    Chromatographia 40 (1995), S. 581-586 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Liquid crystals ; Internal and external NO2 compounds ; Transition temperature ; Analytical properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Thermal and analytical properties of two liquid crystals containing internal [2-nitro, 3-methyl 4-(4-heptylbenzoyloxy) 4′-methylazobenzene] and external NO2 [2,3-dimethyl 4-(4-heptylbenzoyloxy) 4′-nitroazobenzene] have been investigated by gas chromatography. Transitions temperatures are determined by inverse gas chromatography using standard columns. Good agreement with values determined by differential scanning calorimetry are found. Analytical capabilities of the two liquid crystals are shown in glass capillary columns. Compared to examples in the literature, the crystals used separated different kinds of solutes. In addition, high molecular mass solutes were eluted at relatively low temperatures. Typical separations are observed for hydrocarbon positional isomers, aromatic hydrocarbons, geometric isomers, and volatile aroma compounds. Comparison between the performance of internal and external, NO2-liquid crystals is made.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290272
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  • 15
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    Electronic Resource
    Determination of volatiles in spirits using combined stationary phases in capillary GC (1995)
    Springer
    Chromatographia 41 (1995), S. 722-725 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Mixed stationary phases ; Distilled beverages ; Direct analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The analysis of spirits with a single stationary phase is still an unsolved problem; the two amyl alcohols, ethyl acetate and acetal are not separated on a polar column, methanol and acetaldehyde coelute from an apolar column. Trials with coupled columns of different polarities showed that optimum results were obtained with a 40 m capillary column, comprising 6 m of Carbowax 20 M, 12 m of 1∶1 Carbowax 20M:OV1 mixture and 30 m of PS 264. Best results were achieved when a 1 m retention gap was used, injecting a small amount of sample and using a 7 cm syringe needle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267811
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  • 16
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    Quantitative determination of toxic mono- and non-ortho polychlorinated biphenyls in cod liver oil after selective liquid chromatographic separation (1995)
    Springer
    Chromatographia 41 (1995), S. 585-593 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Column liquid chromatography ; Polychlorinated biphenyls ; Cod liver oil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary By application of a chromatographic column filled with Supelclean ENVI-Carb/Celite and elution with three solvents of different polarity three PCB fractions were obtained. Fraction A contained poly-ortho PCBs, Fraction B mono-ortho PCBs, and Fraction C non-ortho PCBs. The Supelclean ENVI-Carb/Celite column was used in combination with a sample preparation procedure for pre-cleaning of acid-stable chlorinated hydrocarbons such as DDT and its metabolites, HCH isomers, and regulation-relevant PCB congeners. The method was optimized using standard solutions of 55 PCB congeners, 8 chlorinated pesticides and contaminated cod liver oil samples. The influence of traces of remaining matrix on the elution profile of the organochlorine compounds on Supelclean ENVI-Carb/Celite was observed. Quantitation was carried out by GC-ECD with fused silica capillary columns of different polarity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269724
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  • 17
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    The stability of selected herbicides preconcentrated from estuarine river waters on solid-phase extraction disks (1996)
    Springer
    Chromatographia 42 (1996), S. 72-76 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Estuarine waters ; Solid-phase extraction ; Triazines, alachlor, metolachlor ; Nitrogen phosphorus detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The stability of atrazine, simazine, alachlor, metolachlor, and deethylatrazine on C18 Empore disks has been determined. Estuarine water (100 mL) spiked at 3 μg L−1 with the target pesticide mixture was preconcentrated on the disks; the disks were then stored at −20°C, 4°C, and at room temperature for periods up to three months and were analyzed by gas chromatography with nitrogen-phosphorus detection. Complete recovery was observed after storage at −20°C throughout the period of the study. Losses up to maximum of 10% were observed after storage at 4°C. Higher losses (up to 24% for alachlor) occurred only at room temperature; the coefficient of variation for these determinations (8–11%) was also higher than that for the others (3–5%). The stability of the pesticides was dependent on the water matrix, on storage temperature, and on properties such as vapor pressure and water solubility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02271058
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  • 18
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    Contribution to the unified retention data of hydrocarbons on squalane (1996)
    Springer
    Chromatographia 42 (1996), S. 660-664 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Unified retention data ; Alkanes, alkenes, naphthenes and aromatics ; Squalane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gas chromatographic, unified retention data of 120 hydrocarbons including: alkanes, alkenes, alkynes, alkylcycloalkanes, alkylcycloalkenes, aromatics and dienes on squalane stacionary phases are given. These values agree well with the corresponding experimental values used in the statistical treatment of the experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267698
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  • 19
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    Structure-retention relationships in the gas chromatography of N,N-dialkylhydrazones (1996)
    Springer
    Chromatographia 42 (1996), S. 653-659 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Dialkylhydrazones ; Kováts retention indices ; Structure-retention relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary N,N-Dialkylhydrazones [DAHs; R1R2C=1N-2N(R3)2] were prepared and their Kováts retention indices determined on 100% dimethylpolysiloxane (HP-1) and 5% diphenyl and 95% dimethylpolysiloxane (HP-5) stationary phases. The physico-chemical and retention behaviour of the DAHs depend greatly on whether R2=H or an alkyl group. A similar difference is observed in the alkane and oxo homomorphic factors of DAHs formed from aldehydes or ketones. The difference is explained on the basis of NMR and quantum-chemical results by intramolecular interactions between R2 and the lone pair of the2N atom. A single linear equation is suitable for prediction of retention indices if parameters are introduced representing resonance structure (bond angle and electron density) besidesI oxo or the van der Waals' surface.
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    URL: http://dx.doi.org/10.1007/BF02267697
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  • 20
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    Temperature programmed gas chromatography of alcohols on cellulose tribenzoate (1996)
    Springer
    Chromatographia 42 (1996), S. 462-464 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Alcohols ; Cellulose tribenzoate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Cellulose tribenzoate (CTB) has some desirable operational properties and special interactions with alcohols. When chromatographic separation is carried out at 150°C, the C1–C4 alcohols have enhanced retention and other alcohols are eluted rapidly. Some probe molecules were used to characterize the chromatographic behavior of CTB by calculating the adsorption enthalpy (−ΔHa) between the sample and stationary phase. Separation of aliphatic alcohols was successfully performed on a packed column with a support (GDX) coated with CTB and temperature programming improved the separation of these alcohols.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272139
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  • 21
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    Gas chromatographic determination of rate constants in bimolecular gaseous reactions (1996)
    Springer
    Chromatographia 42 (1996), S. 441-450 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Reversed-flow technique ; Rate constants ; Bimolecular gaseous reactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Rate constants for bimolecular reactions in the gas phase, under diffusion controlled conditions, can easily be determined by the reversed-flow gas chromatography (RF-GC) technique. The analysis of the diffusion band by means of a simple PC programme gives directly an apparent, second-order rate constant for gaseous reactions. By varying the amounts of the reactants, one can calculate the true order of the reaction and the true non-first-order rate constant of gaseous reactions. The calibration problem of the analytical techniques in non-first-order reaction kinetics is absent as are other disadvantages connected with carrier gas flow, peak shape and their instrumental spreading. The method can be used for atmospheric reactions and was applied in the gaseous reaction systems: SO2+NO2, SO2+Br2, C6H6+NO2, C6H5CH3+NO2 and C3H6+NO2 with various concentrations of reactants in nitrogen. The effect of the NO2 concentration on the apparent second-order rate constant of C2H4+NO2 at 333.2 K was also studied. Finally, the effect of sun light pre-irradiation of C2H2+NO2 in nitrogen was investigated.
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    URL: http://dx.doi.org/10.1007/BF02272137
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  • 22
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    A simple detection system for gas chromatography based on molecular absorption spectrometry in the gas phase (1996)
    Springer
    Chromatographia 42 (1996), S. 435-440 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Molecular absorption spectrometry ; Gas phase detection ; Benzene derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and inexpensive detection system for gas chromatography, based on gas-phase, molecular absorption measurements, is presented in which the chromatographic column is directly joined to the spectrophotometer flow cell, without heated transfer lines. A mixture of eight benzene compounds (including methyl, halogen and nitrogen derivatives) were separated and analyzed. Parameters affecting separation (temperature program and carrier gas flow) and measurement quality (wavelength and integration time) were studied and a measurement program designed to modify the wavelength during chromatography. The analytical characteristics of each compound were calculated, obtaining detection limits ranging from 0.5 to 9 μg mL−1. Finally, the method was applied to several synthetic mixtures, with good results.
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    URL: http://dx.doi.org/10.1007/BF02272136
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  • 23
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    Gas chromatographic separation of low-boiling pyridine bases (1996)
    Springer
    Chromatographia 42 (1996), S. 465-468 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Packed column separations ; Pyridine and alkylpyridines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The gas chromatography of the β-picolines in a lowboiling tar base fraction, is described. The methods developed employ packed columns with binary phases containing N,N,N′,N′-tetrakis(2-hydroxypropyl) ethylenediamine plus metal transition stearate, or with a ternary phase containing this mixture and o-hydroxyethylresorcinol
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    URL: http://dx.doi.org/10.1007/BF02272140
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    Supercritical fluid extraction of chlorothalonil residues from apples (1996)
    Springer
    Chromatographia 42 (1996), S. 547-550 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Supercritical Fluid Extraction ; Pesticides Residues ; Chlorothalonil ; Appels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method for the extraction of Chlorothalonil residues from apples using supercritical CO2 as the extracting fluid is described. The supercritical fluid extraction results were compared with those obtained by solid-liquid extraction. The results showed that SFE is faster and more selective with better recovery and higher selectivity.
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    URL: http://dx.doi.org/10.1007/BF02290289
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    Low-level determination of EDTA and DTPA in natural waters by gas chromatography (1996)
    Springer
    Chromatographia 42 (1996), S. 578-582 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; EDTA determination ; DTPA determination ; Water analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new analytical method and the method validation for the determination of ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) in lake and sea water is presented. An aqueous sample, after evaporation to dryness, was treated with an esterification reagent. The resulting ethyl ester derivates were determined by capillary gas chromatography using a nitrogen phosphorus specific detector (GC-NPD). The response was linear up to 5 mg L−1. The recoveries from lake and sea waters were 59–105 % for EDTA and 86–112 % for DTPA. The run-to-run repeatabilities (R.S.D.) were 2–8 % for EDTA and 4–11 % for DTPA depending on concentration and the reproducibilities (R.S.D.) were 6–13 % and 3–11 %, respectively. The limits of detection for EDTA and DTPA were 3 and 12 μg L−1 in distilled water, respectively. The method is simple to use and reliable as shown by the analysis of samples of lake water that is influenced by pulp and paper industry.
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    URL: http://dx.doi.org/10.1007/BF02290295
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    Comparison of GC-ECD, GC-MS and GC-AED for the determination of polychlorinated biphenyls in highly contaminated marine sediments (1996)
    Springer
    Chromatographia 43 (1996), S. 44-52 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Electron capture detection ; Mass spectrometric detection ; Atomic emission detection ; PCBs in marine sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Electron capture detection (ECD), low- and highresolution mass spectrometry (LR- and HRMS), and atomic emission detection (AED) were compared for the gas chromatographic (GC) detection of polychlorinated biphenyls (PCBs) present in highly contaminated marine sediments. With ECD, LRMS, and even HRMS, detection was seriously disturbed by the complex matrix of the sediments, whereas AED in the chlorine-selective mode provided excellent PCB profiles without interferences. In addition, GC-AED provided congener independent responses, which enabled accurate quantitation of all PCBs based on a single calibration curve. However, because GC-AED was less sensitive than the other techniques studied, preparation of relatively large amounts of sample (10–20 g dry sediment) was required for most analyses.
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    URL: http://dx.doi.org/10.1007/BF02272820
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    Spatial average velocity of carrier gas is proportional to column pressure drop (1996)
    Springer
    Chromatographia 43 (1996), S. 73-75 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Spatial average gas velocity ; Temporal average gas velocity ; Column pressure drop
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary While the commonly known temporal average velocity of a carrier gas is approximately proportional to the pressure drop along a column, the spatial average velocity is exactly proportional to that pressure.
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    URL: http://dx.doi.org/10.1007/BF02272824
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    Automatic preconcentration of chlorophenols and gas chromatographic determination with electron capture detection (1996)
    Springer
    Chromatographia 43 (1996), S. 633-639 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Electron capture detection ; Solid phase extraction ; Chlorophenols ; Water analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A solid-phase extraction system coupled to a gas chromatograph fitted with an electron capture detector was developed for the determination of chlorophenols in waters. The continuous system consists of an XAD-2 adsorbent column where chlorinated phenols are preconcentrated and subsequently eluted with ethyl acetate. The sensitivity of the method is proportional to the number of chlorine substituents in the phenol; thus, the detection limit for monochlorophenols is ca. 10 μg L−1 and that for pentachlorophenol about 2 ng L−1. The method was used to determine chlorophenols in treated waters, with good precision; however, no mono or dichlorophenols were detected at the levels afforded by the proposed method.
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    URL: http://dx.doi.org/10.1007/BF02292980
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    Correlation equations describing retention index data forn-alkylcyclopentenes,n-alkylcyclohexenes andn-alkyl esters on OV-101, OV-225 and PEG 20M (1996)
    Springer
    Chromatographia 43 (1996), S. 557-558 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention indices ; Correlation equations ; n-Alkylcyclopentenes andn-alkylcyclohexenes ; n-Alkyl esters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Correlation equations have been derived which relate the Kováts retention indices ofn-alkylcyclopentenes,n-alkylcyclohexenes andn-alkyl esters of aliphatic acids on the stationary phases OV-101, OV-225 and PEG 20M to column temperature and carbon number in the alkyl chain. The universal equation: $$\begin{gathered} RI = A + B \cdot m + C \cdot \log (m)/m + \hfill \\ D/[(m - 2)^2 + 0.1] + Et \hfill \\ \end{gathered} $$ whereA, B, C, D andE are correlation coefficients,m is the number of carbon atoms in the side chain (forn-alkylcycloalkenes) or in the alcohol chain (for alkyl esters) andt is the column temperature, describes the retention indicesRI of these homologous series with high accuracy (SD〈1 index unit), beginning with the first members of the series.
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    URL: http://dx.doi.org/10.1007/BF02293010
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    Enantiomeric separation of racemic sulphoxides on chiral stationary phases by gas and liquid chromatography (1997)
    Springer
    Chromatographia 44 (1997), S. 91-96 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Liquid chromatography ; Racemic sulphoxides ; Enantiomer separation ; Preparative LC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The enantiomeric resolution of seven racemic sulphoxides on chiral stationary phases has been investigated by gas and liquid chromatography. In gas chromatography the separations were performed on octakis-(2,6-di-O-pentyl-3-O-butyryl)-γ-cyclodextrin (FS Lipodex-E) and heptakis-(2,6-di-O-methyl-3-O-pentyl)-β-cyclodextrin (DMP-β-CD). Both stationary phases were suitable for separation of the enantiomers of the sulphoxides. With one exception for each series all racemetes could be resolved on both stationary phases; FS Lipodex-E was more enantioselective than DMP-β-CD, whereas the latter seemed more generally applicable. Liquid chromatographic separations with Chiralcel-OB as stationary phase were significantly improved by optimization of mobile phase composition and temperature. Resolution factors up to Rs=6 were achieved indicating that the improved separations could now be easily used for preparative purposes.
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    GC determination of volatile components in human exhalation and in ambient atmosphere, after preconcentration on solid sorbents (1997)
    Springer
    Chromatographia 44 (1997), S. 601-604 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Trace volatile components ; Human breath
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A modified GC sampling system and its analytical use are described for the determination of volatile components of human breath or in ambient atmosphere with flame-ionization detection (FID). The difficulties of collection for low concentration samples were alleviated by using a very small trapping column packed with activated charcoal. The collected samples can be measured directly after thermal desorption onto the chromatographic column (packed with Porapak Q). The preconcentration recoveries for pentane, methanol, ethanol and acetone have been studied.
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    Gas chromatographic (GC) method for the determination of SCH 44643, an orally active antagonist of platelet activating factor in rat plasma (1996)
    Springer
    Chromatographia 43 (1996), S. 533-536 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid phase extraction ; Nitrogen phosphorus detector ; SCH 44643 in rat plasma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A gas chromatographic (GC) assay for the determination of SCH 44643, an orally active antagonist of responses to both histamine and PAF, was developed and validated for rat plasma. The method involved organic solvent extraction followed by solid phase extraction on aminopropyl column. The separation was on a capillary column (DB-17) with quantitation by a nitrogen-phosphorus detection. The method was sensitive with a limit of quantitation of 5 ng mL−1. There was a good linear relationship between the peak height ratio (SCH 44643/internal standard) and SCH 44643 concentration in the range 5 to 200 ng mL−1. The method was precise with a coefficient of variation ranging from 1.8 to 3.0% and accurate with a bias ranging from 0 to 5.8%. Moreover, SCH 44643 was stable in rat plasma after being subjected to three freeze-thaw cycles. The assay was shown to be sensitive, specific, accurate and precise, and suitable for use in pharmacokinetic or toxicokinetic studies.
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    Gas chromatographic properties of two thermotropic Poly(L-glutamates) with long alkyl side chains (1996)
    Springer
    Chromatographia 43 (1996), S. 387-392 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Poly(L-glutamate) ; Cholesteric liquid crystal ; Properties as stationary phases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Comparative gas chromatographic properties of two thermotropic Poly(L-glutamates) with long alkyl side chains (10 and 16 carbons called Poly 10 and Poly 16 respectively) are studied. Their thermal properties were established with differential scanning calorimetry (DSC) and gas chromatography. They present a cholesteric liquid crystal in a large temperature range. The chromatographic separation abilities of the two polymers in the liquid crystal state were studied using capillary glass columns. Interesting analytical performances were obtained in different fields: isomeric separation of alkanes, aromatics, polyaromatics, volatile aroma compounds and cis and trans isomers. Some differences were noticed in their behaviours; 2 and 3-methyloctane and xylene isomers are separated only on Poly 10 while limonene and eucalyptol are separated only on Poly 16.
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    Simultaneous determination of aliphatic hydrocarbons, PCBs and PCTs in pork liver by gas chromatography (1996)
    Springer
    Chromatographia 43 (1996), S. 398-400 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Aliphatic hydrocarbons ; Chlorinated aromatics ; Pork liver extracts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A multicomponent extraction/concentration procedure has been developed for the enrichment of PCBs, PCTs and aliphatic hydrocarbons (pristane, C18, C19, C20, C22, C24, C28, C32 and C36) in pork liver. These components of the enriched extract were then simultaneously determined by gas chromatography. Mean recoveries ranged from 81.5% for pristane to 93% for PCBs;CV% (0.9–6.7) indicated the method to be both precise and reproducible.
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    Evaluation of improved method for determination of rapeseed-mustard FAMEs by GC (1997)
    Springer
    Chromatographia 44 (1997), S. 97-99 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; FAMEs ; Rapeseed-mustard ; Half-seeds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An efficient and economical GC method for rapid determination of FAMEs in rapeseed-mustard is described. The seeds were transmethylated with acetylchloride, using microwave heating and separation achieved on a 3 m column packed with a mixture of 2% SP-2300 and 3% SP-2310 on Chromosorb ‘W’. The method is compared with the conventional heating method and extended efficiently for half-seed analysis. The fatty acid composition of the FAMEs mixtures prepared by both methods was similar with highly significant correlation coefficients (P〈0.001).
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    The true physical meaning of the corrected retention volumes in GC (1997)
    Springer
    Chromatographia 44 (1997), S. 279-282 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention volumes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Through a straightforward mathematical derivation it is shown that the compressibility correction factor equals the ratio of gas pressure at the column outlet to the average pressure in the column, $$j = p_0 \sqrt p $$ . Therefore, by multiplying by this factor, the experimentally measured retention volumes can be recalculated to the average pressure in the column. Corrected retention volumes thus represent the volume of the mobile phase under real conditions of chromatography in the column. Appropriate definitions for corrected retention volumes and factorj are formulated.
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    On-line solid-phase extraction-gas chromatography-ion trap tandem mass spectrometric detection for the nanogram per liter analysis of trace pollutants in aqueous samples (1997)
    Springer
    Chromatographia 44 (1997), S. 372-380 
    Details
    ISSN: 1612-1112
    Keywords: Solid-phase extraction ; Gas chromatography ; Ion trap tandem mass spectrometry ; Water samples ; Environmental analysis ; Pesticides ; Bromide ; Nitrite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary On-line solid-phase extraction-gas chromatographyion-trap tandem mass spectrometry (SPE-GC-MS/MS) has been used for the trace-level determination of polar and apolar pesticides. The SPE-GC interface, an Autoloop 2000, was operated at an injection temperature of 90°C which permitted the determination of thermolabile pesticides such as carbofuran and carbaryl. Rectilinear calibration curves were obtained for the analytes tested over a range of 0.1–500 ng L−1, using a sample volume of 10–100 mL for enrichment on an SPE cartridge packed with styrene-divinylbenzene copolymer. The detection limits for the pesticides were in the 0.01–4 ng L−1 range. For a number of pesticides acceptable tandem mass spectra were obtained at levels as low as 0.1 ng L−1 level in real-life water samples. As a demonstration of the applicability of this technique for inorganic anions, bromide and nitrite were converted into 4-bromoacetanilide and 2-phenylphenol, respectively. The reaction products were pooled and subjected to simultaneous analysis by the present method using full-scan mass spectrometric detection. The detection limits were 0.3 and 2 ng L−1, respectively.
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    Direct GC determination of methylmercury chloride on HBr-methanol-treated capillary columns (1997)
    Springer
    Chromatographia 44 (1997), S. 386-392 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; HBr-treated capillary column ; Methylmercury chloride ; Halide exchange ; ECD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gas chromatography with electron capture detection (GC-ECD) for the analysis of methylmercury choloride (MMC) using a packed column and a capillary column has been investigated. The columns were 2% silicone OV-227 Uniport HP glass column and a DB-17 capillary column, each pretreated by about ten injections of HBr-methanol solution. MMC was separated as a sharp peak by the HBr-teated column and determined directly by ECD without derivatisation. The mass spectrum of MMC indicated that halide exchange from chloride to bromide proceeded during separation. The minimum detectable concentrations were approximately 5 ng mL−1 on the packed column, and 2 ng mL−1 on the capillary. Calibration curves showed good linearity between 5–200 ng mL−1 for the packed column, and between 2–200 ng mL−1 for the capillary. Relative standard deviations of peak areas were 0.95% for the packed column and 0.43% for the capillary at the level of 100 ng mL−1 in both cases. The column treatment technique was applicable to determination of methylmercury in fish samples.
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    Evaluation of capillary gas chromatography for the measurement of hydrocarbons by participating in an intercomparison experiment (1997)
    Springer
    Chromatographia 44 (1997), S. 405-410 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Tenax-TA sampling ; Thermal desorption ; Preconcentration ; Flame ionization detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary By participating in an International Hydrocarbons Intercomparison Experiment, a method for the determination of nonmethane hydrocarbons was evaluated. The method involves Tenax-TA sampling, thermal desorption and preconcentration combined with capillary gas chromatography with flame ionization detection. Sixty target compounds from C2 to C11 were separated by using a megabore capillary column with a thick film of bonded nonpolar siloxane stationary phase (5 μm, Rtx-1). The unusually thick film in the column was an advantage for resolving light hydrocarbons (C2−C3) at room temperature. The percent difference between the National Institute of Standards and Technology (NIST) and our laboratory in the intercomparison experiment is in the range of 0.99%–19.70%.
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    Synthesis and characterization of modified silica gel as an intermediate in the generation of gaseous standard mixtures (1997)
    Springer
    Chromatographia 44 (1997), S. 484-490 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Modified silica gel ; Gaseous standard mixtures ; FID calibration ; Methyl chloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A possibility of extending analytical applications of chemically modified silica gels is described. This involves their utilization for the generation of gaseous standard mixtures consisting of methyl chloride as the analyte and nitrogen as a carrier gas to be used for the calibration of the GC-FID system. N-methylmorpholine was chemically bonded to the propylsilylated surface of silica gel forming chloride of an appropriate immobilized compound which, under certain conditions, undergoes thermal decomposition yielding a single, volatile component (methyl chloride). Such a method of generating specific amounts of a standard substance can be used both for a single point calibration and for checking the accuracy of an analytical instrument in a relatively wide measurement range. It was found that 3.40±0.081 mg of methyl chloride can be generated per 1 g of the modified gel.
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    Analysis of organophosphorus, organochlorine and pyrethroid insecticides in medicinal plants (1997)
    Springer
    Chromatographia 44 (1997), S. 505-513 
    Details
    ISSN: 1612-1112
    Keywords: Colum liquid chromatography ; Gel permeation chromatography ; Gas chromatography ; Organophosphorus, organochlorine and pyrethroid pesticides ; Multiresidue analysis in medicinal plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Multiresidue analysis of organophosphorus, organochlorine and pyrethroid pesticides in medicinal plants, gives problems of extraction, purification and detection. Analytical methodologies have been developed for vervain and tested for camomile and peppermint without prior knowledge of the pesticides used in their treatment. Extraction is common to all three pesticide families: acetone or acetonitrile is chosen depending on the particular matrix. Isolation of organophosphorus compounds is performed by gel permeation chromatography. Organochlorine and pyrethroid pesticides are extracted in two steps: gel permeation followed by adsorption chromatography on silica el cartridges. Analysis and detection of organophosphorus compounds is by gas chromatography with a nitrogen phosphorus detector; organochlorine and pyrethroid compounds are identified by gas chromatography with an electron capture detector.
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    Comparison of GC-MS and HPLC for overcoming matrix interferences in the analysis of PAHs in smoked food (1997)
    Springer
    Chromatographia 44 (1997), S. 497-504 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Gas chromatography-mass spectrometry ; Column liquid chromatography ; Polycyclic aromatic hydrocarbons ; Food analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Several separation and detection methods for polycyclic aromatic hydrocarbons (PAHs) in smoked chicken by GC and HPLC were compared. With HPLC and a gradient solvent system, all 16 PAHs could be simultaneously separated and detected by fluorescence with seven settings of programmable wavelength (excitation/emission). The presence of impurities in smoked chicken could interfere with the subsequent identification and quantification of PAHs by HPLC. With GC and a temperature programming method, all 16 PAHs could be separated and the PAHs in the chicken sample could be detected with an ion-trap mass spectrometer even in the presence of fat-or PAH-like impurities. Nine PAHs were identified by the former method while fourteen PAHs were identified by the latter method. The retention times by HPLC were shorter than those by GC, also, the former had better separation for most PAHs than the latter.
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    Large-volume PTV injection: Comparison of direct water injection and in-vial extraction for GC analysis of triazines (1998)
    Springer
    Chromatographia 47 (1998), S. 35-41 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Programmed-temperature vaporization (PTV) ; Large-volume injection ; Direct water injection ; Triazines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The potential of large-volume PTV injection was studied for the analysis of triazine herbicides in water samples. Direct water injection and in-vial extraction were described and compared. Detection limits were between 0.01–0.02 μg L−1 and relative standard deviations were 〈9%. Both methods are suitable for the analysis of triazines at ppt-level, although in-vial extraction is favourable for water samples with relatively large amounts of matrix components.
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    Development of gas chromatographic method for determination of cholesterol oxides in meat products (1998)
    Springer
    Chromatographia 47 (1998), S. 42-48 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Cholesterol oxides ; Cholesterol oxidation products (COPs) ; Meat products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method of extraction, purification and gas chromatographic analysis of five cholesterol oxidation products (COPs) (7β-hydroxycholesterol, 5α, 6α-epoxycholesterol, 25-hydroxycholesterol, 7-ketocholesterol and cholestane-3β, 5α, 6β-triol) has been developed. The method is aimed at the determination of COPs in meat and meat products, in particular dry sausages, where large differences in the content of cholesterol and its oxidation derivatives may occur. Linearity of response of trimethylsilyl ethers was defined. The minimum concentration tested was 2.5 μg g−1 in the injected solution. The main feature of the present work is the addition of a purification step of unsaponifiables by SPE on silica cartridges. Extraction recoveries of COP standard mixtures, performed with or without the SPE step, are evaluated. The introduction of the clean-up step results in high purity samples without further losses in the entire process.
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    Determination of aliphatic and aromatic aldehydes in cigarette smoke by gas chromatography with flame photometric detection (1997)
    Springer
    Chromatographia 44 (1997), S. 491-496 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Aliphatic and aromatic aldehydes ; Thiazolidine derivatives ; Flame photometric detection ; Cigarette smoke
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A selective and sensitive method for the simultaneous determination of aliphatic and aromatic aldehydes in cigarette smoke by gas chromatography (GC) has been developed. After trapping of cigarette smoke into dilute hydrochloric acid containing ascorbic acid, aldehydes were converted into their thiazolidine derivatives by the reaction with cysteamine, and then measured by GC with flame photometric detection using two-connected fused-silica capillary columns containing DB-17 and DB-210, respectively. The derivatives were sufficiently volatile and gave single symmetrical peaks. The calibration curves for aliphatic and aromatic aldehydes in the range 20–2000 ng were linear and the detection limits at a signal-to-noise ratio of 3 were ca. 4–100 pg injected. Aliphatic and aromatic aldehydes in cigarette smoke could be selectively determined by this method without any interference from coexisting substances. Overall eecoveries of aldehydes added to cigarette smoke samples were 83–110%. Analytical results for the contents of aliphatic and aromatic aldehydes in mainstream and sidestream smokes of several cigarettes are presented.
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    Fast determination of VOCs in workplace air by solid-phase extraction and gas chromatography-mass spectrometry (1998)
    Springer
    Chromatographia 47 (1998), S. 57-62 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid-phase extraction ; Graphitized carbon black ; Volatile organic compounds ; Workplace air
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A fast, simple, and reliable method is presented for the determination of atmospheric semi-volatile organic pollutants at μg m−3 levels. The method has been used to monitor potentially carcinogenic toxic compounds to which workers are exposed in workplaces, and to measure the same compounds in outdoor air.
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    Interaction studies of vinychloride with liquid foods by gas chromatography (1998)
    Springer
    Chromatographia 47 (1998), S. 63-71 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Liquid foods ; Food packaging materials ; Vinylchloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The interaction of vinylchloride (VC) with liquid foods, such as water, olive oil and honey, was studied using the relatively new technique of Reversed-Flow Gas Chromatography (RFGC). The RFGC method permits the calculation of the VC diffusion coefficient in the liquid phase (water, oil and honey) and the determination of the partition coefficient of VC between the liquid and the carrier gas, as well as the determination of the Henry's constant of VC in the liquid food. From the variation of the above parameters with temperature, thermodynamic parameters (free and excess free energies, enthalpies, entropies and activity coefficients) were calculated for the adsorption of VC by liquid foods. These are discussed in comparison with the same parameters calculated from empirical equations or determined experimentally by other techniques.
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    Fundamental relationships in gas chromatography (1998)
    Springer
    Chromatographia 47 (1998), S. 570-574 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Compressibility correction factor ; Specific retention volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The exact definition of the compressibility correction factor,j, has been extensively discussed in recent literature. In this work, it is shown that this compressibility correction factor has several different interpretations; however, the simplest and most useful meaning involves a correction from the experimentally accessible pressure at the outlet of a column to the average pressure in the column. Also, an unconventional definition of the retention volume of a solute in terms of the sample size and the equilibrium concentration of the solute in the mobile phase is presented. This retention volume definition is presented as an alternative to the common definition ofV R as the volume of carrier gas which passes through the column in a period of time called the retention time. In this discussion, it is emphasized that the temeprature dependence of the specific retention volume is determined by the thermodynamics of the phase distribution process for the solute and not by an equation-of-state for the carrier gas. Finally, the conventional correction of the specific retention volume by a factor of 273/T c can be used to correct a volume of carrier gas to a pseudo-standard state of 273 K and the average pressure in the column; however, this corrected specific retention volume has no relation to the specific retention volume that would be experimentally obtained at this standard state temperature and pressure. compressibility correction factor, and specific retention volume, were examined with regard to the physical interpretation, exact definition and appropriate standard states to be applied to these commonly reported chromatographic parameters. Such arcane discussions are beneficial to the health of science but may lead to confusion among potential and practicing chromatographers. In order to prevent or at least help ameliorate this problem, the following discussion presents a somewhat unorthodox interpretation of the questioned terms along with a pseudo-physical explanation of the so-called retention volume which is ubiquitous throughout the chromatographic literature.
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    Determination of chlorobenzenes in environmental samples using solid phase microextraction, thermal desorption and analysis by gas chromatography coupled to FID, ECD, MSD, IRD detectors (1998)
    Springer
    Chromatographia 48 (1998), S. 74-80 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; SPME ; Soil and groundwater samples ; Chlorobenzenes ; Thermal desorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A complex method was developed for the determination of chlorobenzenes in soil and groundwater samples. Samples were taken at two sites in Baranya county, where a mixture of chlorobenzene waste was deposited, causing severe contamination in the environment. Clean-up of these sites demands modern and reliable analytical methods. Several sample preparation techniques were used, such as solid phase microextraction (SPME), supercritical fluid extraction (SFE), and a recently developed thermal desorption method. The applicability of various sample preparation methods was compared by measuring recovery percentages, relative standard deviations and by investigating the matrix dependency of these values. Gas chromatography was used for quantitative determination of chlorobenzenes, using MS, IR, FID and ECD detection techniques. Detection levels were as low as 1 ppt in water, and 10 ppt in soil samples. Chlorobenzene concentration was in the range 1 ppt-1 ppm in water and 100 ppb-100 ppm in soil samples. Identification and calibration of these compounds were performed by quantitative standards. This complex analytical method can be used for rapid and precise quantitative and qualitative determination of chlorobenzenes.
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    Quantitative analysis of apolar polysiloxane phases in large-bore capillary columns (1998)
    Springer
    Chromatographia 47 (1998), S. 305-308 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Silicone phases ; Film thickness ; Large-bore capillary columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A technique is described for determination of the amount of bonded phase in commercial columns. It is adapted to the determination of the real nature and the thickness of a siloxane bonded film. Ten-centimeter samples of column are used. The method is tested for large-bore capillary columns. Applications to kinetic studies are suggested.
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    On-line sample treatment—capillary gas chromatography (1998)
    Springer
    Chromatographia 47 (1998), S. 313-345 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Sample pretreatment ; Coupling on-line to capillary GC ; Robotization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Sample pretreatment is often the bottleneck of a tracelevel analytical procedure. In order to increase performance, increasing attention is therefore being devoted to combining sample pretreatment on-line with the separation technique that has to be used. In the present review, a variety of procedures in use today for sample treatment coupled on-line to capillary gas chromatography (GC) is briefly discussed. Special attention is devoted to coupled-column techniques such as SPE-GC and LC-GC (SPE, solid-phase extraction; LC, column liquid chromatography) which are topics of much current interest, also because of their frequent use in so-called hyphenated systems.
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    Capillary gas chromatography of urinary steroids of terbutaline-treated asthmatic children (1998)
    Springer
    Chromatographia 48 (1998), S. 163-165 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid-phase extraction ; Urinary steroids ; Terbutaline treatment ; Asthmatic children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Steroid metabolites have been measured by capillary gas chromatography in the urine of 38 children aged 3–6 years. The children comprised three groups: those with asthma being treated with Terbutaline (13), children with asthma but not undergoing treatment (17), and control children in hospital but free from endocrine diseases (8). There were significant (P〈0.05) differences between the amounts of steroids excreted by the different groups of children. Terbutaline therapy led to elevated levels of tetrahydrocortisone, androstenediol, 11-ketopregnanetriol and a reduced ratio of androgen to cortisol metabolites compared with those for untreated asthmatic children. We assume that Terbutaline does not have a steroid-like mechanism of action but acts by modification of the activity of several adrenocortical enzymes. We suggest a hypothesis whereby the antiasthmatic effect of Terbutaline could not only be a connected with its well-known mechanism of action, but it might be explained as a result of the modification of the production of certain glucocorticoids and androgen hormones.
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    Separation of positional isomers on polymeric calix[4]arene-siloxane stationary phases in capillary GC (1998)
    Springer
    Chromatographia 48 (1998), S. 422-426 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Calix[4]arene-tetramethyldisiloxane stationary phases ; Geometric and positional isomer separations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Poly(p-tert-butyldimethoxydipropyloxycalix[4]arene-tetramethyldisiloxane) (TBCX-TMDS) and poly(dimethoxydipropyloxycalix[4]arene-tetramethyl-disiloxane) (CX-TMDS), have been prepared and used as stationary phases for isothermal capillary gas chromatographic separations of positional isomers. Retention factors and separation factors for the isomers were measured. The isomers investigated were well-resolved on the two phases. Retention of all the solutes investigated is greater on TBCX-TMDS than on CX-TMDS, probably because of extra dispersive interactions of the solutes with thetert-butyl groups of the phase. Separation factors for closely-eluting isomer pairs are similar on the two phases. This seems to indicate either that the solutes are retained by non-inclusion processes or that if the isomer molecules do enter the cavity of the calixarene, i.e. the solute is retained by inclusion, thetert-butyl groups do not play a role in discriminating between the isomers.
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    Determination of triethanolamine in air samples by gas chromatography-mass spectrometry (1998)
    Springer
    Chromatographia 48 (1998), S. 443-449 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Gas chromatography-mass spectrometry ; Triethanolamine in air
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Low amounts of triethanolamine, collected in ORBO 53 tubes during air sampling, required the development of a very sensitive method for determination. After desorption and silylation reaction with trimethylsilyl imidazole/trimethyl chlorosilane, the derivative was analyzed by gas chromatography-mass spectrometry on an Ultra 2 silica capillary column in single ion monitoring mode (retention time: about 6 min). The method has a detection limit of 1–2 pg with a desorption efficiency of about 81%. Linearity of response was ascertained in the ranges 10–100 ng and 100–1000 ng. Short-term method validation was carried out by intra- and inter-day assays on three amounts for each reference calibration curve. All results satisfied the pre-defined acceptance criteria. In general, the whole procedure was easily performed and was appropriate for our needs. Breakthrough volume was appropriate for our needs. Breakthrough volume was determined on authentic samples and was about 40–60 L, using a flow rate of 1 L·min−1. The amounts of triethanolamine found in the samples ranged from 150 to 250 ng (about 2.5–4.2 μg·m−3).
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    Monitoring of optical isomers of chiral alcohols and derivatives by chiral gas chromatography. Effect of derivatization on the enantio-differentiation (1998)
    Springer
    Chromatographia 48 (1998), S. 81-85 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Chiral separation ; Alcohols ; Diols ; Trimethylsilylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gas chromatographic chiral separation of several chiral 2-and 3-alkanols and diols was studied both in their free hydroxyl and in their trimethylsilyl ether forms. First, the derivatization procedure was verified through the identification of the trimethylsilyl ethers formed on the basis of their mass spectra and optimized to obtain quantitative reaction. The optimized procedure was applied to the trimethylsilylation of racemic mixtures of various hydroxyl compounds. The silylation was found to be highly effective in the improvement of the separation of the individual enantiomers. The major advantages of the derivatization process can be summarized as: (i) excellent baseline separation of the enantiomers of the silyl ethers was achieved in contrast to the parent OH-containing compounds, (ii) the sensitivity of detection highly increased, (iii) the separations do not show any significant concentration dependence and finally (iv) the analysis time needed decreased significantly.
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    Data correlation in on-line solid-phase extraction-gas chromatography-atomic emission/mass spectrometric detection of unknown microcontaminants (1998)
    Springer
    Chromatographia 48 (1998), S. 273-283 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Atomic emission and MS detection ; Solid-phase extraction ; Aqueous samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A procedure is described for the (non-target) screening of hetero-atom-containing compounds in tap and waste water by correlating data obtained by gas chromatography (GC) using atomic emission (AED) and mass selective (MS) detection. Solid-phase extraction (SPE) was coupled on-line to both GC systems to enable the determination of microcontaminants at the 0.02–1 μg L−1 level in 7–50 mL of aqueous sample. The screening was limited to compounds present in at least one heteroatom-selective GC-AED trace above a predetermined concentration level. These compounds were identified by their partial formulae (AED) and the corresponding mass spectra, which were obtained from the GC-MS chromatogram via the retention index concept. The potential of the approach was demonstrated by the identification of target compounds as well as all unknowns present in tap and waste water above the predetermined threshold of 0.05 μg L−1 (tap water) or 0.5 μg L−1 (waste water).
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    Crown ether capped cyclodextrin used as stationary phase for capillary gas chromatography (1998)
    Springer
    Chromatographia 48 (1998), S. 817-822 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Crown ether capped cyclodextrin ; Chiral separations ; Isomer separations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The solution of a new synthesized compound, mono-6-(1'-benzo-aza-15-crown-5)-2, 3, 6- permethyl-β-cyclodextrin, in the moderately polar polysiloxane OV-1701 was coated onto fused silica capillary column. The chromatographic characteristics including column efficiency, polarity and selectivity were studied. Excellent selectivity for the separation of enantiomers and positional isomers was obtained. The results show that the combined effect between the special caves of β-cyclodextrin and crown ether plays a significant role in the separation.
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    Gas chromatography with UV-vis molecular absorption spectrometry detection: Data acquisition and treatment when using a diode-array spectrophotometer (1998)
    Springer
    Chromatographia 48 (1998), S. 535-541 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; UV-Vis detection ; Gas phase absorption spectrometry ; Alcohols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This article describes a theoretical/practical study of the parameters which affect the chromatograms obtained when using a molecular diode-array spectrometer as the detector in gas chromatography. The objective is to offer some rules which permit the identification of the optimum signal/noise relation. To achieve this, we study the effect of the different parameters which affect the noise and how to reduce their impact, as well as alternatives for increasing the signal. All the options tested can be applied by correctly programming the spectrometer with BASIC programs, within reach of any use who has even a small understanding of programming. Finally, we consider the effect that the selection of the acquisition conditions may have on the chromatographic resolution. All the studies are carried out using a mixture of alcohols and phenols.
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    Synthesis of a new liquid crystal, 4-[(4-chlorobenzyl)oxy]-4′-cyanoazobenzene and its use as stationary phase in gas-chromatography (1998)
    Springer
    Chromatographia 48 (1998), S. 427-430 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Liquid crystal stationary phase ; Packed columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation ofm-, p-, o- xylenes andm-, p- ethyltoluenes was studied on a packed column with 2,5% of 4-[(4-chlorobenzyl)oxy]-4′-cyanoazobenzene (CBOCA) on Chromosorb W HP 100–120 mesh. The synthesis and study of the mesomorphic behaviour of CBOCA are presented. Temperature range for the separation ofm-, p-, o- xylenes (in this order of elution) is 125–85°C, at cooling. The best separation was achieved at about 90°C. The separation temperature domain ofm-ethyltoluene fromp- ethyltoluene is 160–85°C.
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    Derivatization of aromatic amines with bromine for improved gas chromatographic determination (1998)
    Springer
    Chromatographia 48 (1998), S. 436-442 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Water analysis ; Derivatization with bromine ; Aromatic amines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary For improved determination of aromatic amines by gas chromatography and detection with an electron capture detector (GC-ECD) a derivatization method based on the bromination of the aromatic ring in an acetic acid medium was developed. In general, all free ortho and para-positions relative to the amino group undergo electrophilic substitution. Separation of at least 30 compounds in a single chromatographic run in 30 min is possible. With this method, 56 aromatic amines were studied and only in 6 cases were no derivatives obtained. Quantitation limits determined from calibration data are 1.2–40 μg L−1 for a 100 mL sample and an injection volume of 1 μL. Previous experiments suggest that both sample and injection volume may be increased to lower the quantitation limit.
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    Effect of organic matter content in the trace analysis of triazines in various types of soils with GC-NPD (1998)
    Springer
    Chromatographia 48 (1998), S. 450-456 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Soil samples ; Microwave-assisted solvent extraction ; Nitrogen detection ; Triazine herbicides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Recent work demonstrated that the combination of microwave assisted solvent extraction (MASE) and capillary gas chromatography with selective nitrogen detection (GC-NPD) is a viable approach for the efficient determination of triazine herbicides in soils. However, for soils with a high organic matter content or the injection of more concentrated extracts to obtain lower LOD's the performance of gas chromatographic analysis of uncleaned extracts is hampered. This results in both a decrease of the chromatographic response of analytes and a decrease in the life time of the column due to coextracted matrix substances. The effect of various types of soils on the chromatographic analysis of triazine herbicides was studied. It appeared that for the investigated samples with an organic matter content below 5% processing of uncleaned extracts is possible. Samples with a higher organic matter content required a cleanup step. A rapid procedure on 100 mg silica cartridges has been developed using solvents compatible with the MASE extracts and the instrumental analysis. Beside the testing with different standard soils, about 120 samples of an ongoing monitoring program involving three different types of soil (organic matter content: 3–37%) were analysed. The selected compounds atrazine, desethylatrazine, desisopropyl-atrazine and simazine could be assayed in the various soil types to a level of at least 2 μg kg−1. For soil samples with a high organic matter content (〉5%), the rapid cleanup procedure allowed the trace analysis of the triazines and considerably increased the life time of the capillary column. Recoveries at levels from 2 to 50 μg kg−1 ranged from 70 to 100% with RSDs ranging from 5.1 to 9.5%. Confirmation of positive samples was carried out by gas chromatography mass spectrometry.
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    Identification and semi-quantitative determination of a migration contaminant from beverage carton packages into mineral water by on-line solid phase extraction gas chromatography-mass spectrometry (SPE-GC-MS) (1998)
    Springer
    Chromatographia 48 (1998), S. 581-583 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; On-line SPE-GC-MS ; Beverage carton packages ; Contaminant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An unknown migration contaminant was found in a number of mineral water samples contained in beverage carton packages. This compound was isolated by a fully automatic solid phase extraction system and identified by means of GC-MS as 2,4,7,9-tetramethyl-5-decyne-4,7-diol (TMDD) [126-86-3], which is used as a surfactant in water-based printing inks and migrates during the production of the beverage carton material into the inner polyethylene film and subsequently into the product. The determined concentrations of TMDD ranged up to more than 50 μg L−1.
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    Monitoring of nicotine in air using sorptive enrichment on polydimethylsiloxane and TD-CGC-NPD (1999)
    Springer
    Chromatographia 49 (1999), S. 520-524 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Sorptive preconcentration ; Air monitoring ; Nicotine ; Hospital air
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A novel method for the enrichment of nicotine from gaseous samples is presented. It is based on the sampling of 6 liters of air onto a cartridge packed with 100% polydimethylsiloxane (PDMS) particles. The analytes are dissolved (partitioned) into the PDMS phase which results in much better recoveries and reproducibilities compared to those obtained on common adsorbents. The PDMS tube is then placed in a thermal desorption (TD) unit connected to a CGC-NPD or CGC-MS system. The procedure was employed for routinely monitoring air in a hospital. Nicotine was typically found at levels ranging from 5 to 250 μg m−3 (ppb) depending on the location and number of smokers present. Additionally, the efficiency of nicotine filters was determined by sampling simultaneously at the filter in- and outlet and was found to be 46%.
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    High temperature capillary GC analysis of phytopreparations of “espinheira santa” (Maytenus ilicifolia M. andMaytenus aquifolium M. — Celastraceae), a Brazilian antiulcer plant (1995)
    Springer
    Chromatographia 40 (1995), S. 341-344 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Pentacyclic triterpenes ; Maytenus aquifolium Martius ; Maytenus ilicifolia Martius ; Phytopharmaceuticals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary We report a method for the analysis of triterpenes in aqueous alcoholic extracts ofM. ilicifolia orM. aquifolium leaves, using high temperature capillary gas chromatography in polar columns (OV-17-OH). These species are popularly known in Brazil as “espinheira santa” and have proven antiulcer properties. The method consists of the pre-concentration of the triterpenes from the aqueous alcoholic extract, followed by GC analysis, which permits the determination of the presence of friedelan-3-ol and friedelin. Direct comparison with several triterpenol standards that are usually found in falsified “espinheira santa” samples but are absent in the authentic drug, showed that GC analysis clearly allows detection of the presence of friedelan-3-ol and friedelin and, therefore, permits distinguishing between authentic and false “espinheira santa” aqueous alcoholic extracts.
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    Rapid multiresidue screening method for organophosphate pesticides in vegetables (1995)
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    Chromatographia 40 (1995), S. 417-420 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Organophosphate pesticides ; Vegetables ; Pesticide residue analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid and efficient multiresidue extraction procedure using ethyl acetate and sodium sulfate has been applied to the analysis of diazinon, methamidophos, chlorpyrifos, malathion, parathion, parathion-methyl, dimethoate and monocrotophos residues in many different kinds of vegetables. No cleanup step was required Concentrated extracts were analysed by gas chromatography with flame photometric detection in phosphorus mode. Recovery studies were performed in six kinds of matrices at two fortification levels. Recoveries were in the range 80–115%. The limit of quantification of the analytical method has been estimated as 0.01 ppm for diazinon, methamidophos and malathion, 0.03 ppm for chlorpyrifos, parathion, parathion-methyl and dimethoate and 0.1 ppm for monocrotophos. Experiments showed that potentially it should be possible to develop a rapid and universally applicable method for organophosphate pesticide residues in different matrices.
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    A gas chromatographic flow method for preconcentration and determination of vitamins D2 and D3 in pharmaceutical preparations (1995)
    Springer
    Chromatographia 40 (1995), S. 425-431 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Continuous preconcentration method ; Vitamins D2 and D3 ; Pharmaceutical preparations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A continuous-flow method that combines on-line preconcentration and isolation with gas chromatography for the direct determination of vitamins D2 and D3 in oily solutions is reported. A silica gel column permits preconcentration and isolation of analytes from the vitamin D matrix, although some triglyceride (ca. 25%) is also retained. To overcome problems associated with the low volatility of triglycerides, their retained fraction is further transesterified with potassium methylate to fatty acid methyl esters after elution. The proposed method was applied to the determination of vitamin D in pharmaceutical preparations.
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    Determination of cholesterol in milk fat by gas chromatography with direct injection and sample saponification (1995)
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    Chromatographia 41 (1995), S. 23-28 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Cholesterol ; Direct injection ; Saponification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid and direct gas chromatographic (GC) method for determining free cholesterol in milk fat using a capillary column and programmed-temperature vaporizerinjector was assayed. It was compared with other procedures involving saponification of fat, solvent extraction of unsaponifiable matter—with and without fractionation by thin-layer chromatography—and transformation of sterols into silyl derivatives prior to GC analysis. This paper proposes an alternative to other published procedures. Repeatability of the method was assessed and the coefficient of variation determined as 2.1%. The alternative saponification method exhibited comparable accuracy (coefficient of variation=1.8%). Recovery ranged from 99.1% to 105.6%.
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    URL: http://dx.doi.org/10.1007/BF02274190
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    Specific interactions of n-donor adsorbates with N-benzoylthiourea-copper(II) complexes chemically bonded to silica supports (1995)
    Springer
    Chromatographia 41 (1995), S. 107-111 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Metal complex stationary phases ; Specific interactions ; N-benzoylthiourea groups
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Silica was modified with γ-aminopropyltriethoxylsilane, and then the amino group was converted into an N-benzoylthiourea compound. Treatment with anhydrous CuCl2 solution, gave a copper(II) complex on the surface. In order to estimate the ability of the complex to interact specifically with electron donors, a number of retention parameters were determined for three groups of compounds showing electron-donor properties: ketones, ethers and nitroalkanes. On the basis of the results, the effect of adsorbate structure on the strength of specific interactions was established. The packings studied may be useful for the analysis of the mixtures of ketones, ethers, and nitroalkanes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274203
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    Analysis of pesticide residues in fruit and vegetables by matrix solid phase dispersion (MSPD) and different gas chromatography element-selective detectors (1995)
    Springer
    Chromatographia 41 (1995), S. 685-692 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Matrix solid phase dispersion (MSPD) ; Fruit and vegetables ; Pesticide residues ; Selective detectors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A comparison between different element selective detectors for the determination of organophosphorus and organochlorine pesticide residues, from fruit and vegetables, was performed by capillary GC with electron capture detector (ECD), nitrogen phosphorus detector (NPD), flame photometric detector (FPD) in the sulphur and phosphorus modes, and mass spectrometry detector (MSD) in selected ion monitoring (SIM) mode. Pesticides were extracted from the different foodstuffs by Matrix Solid Phase Dispersion (MSPD). Recoveries of 41–108 % with relative standard deviation of 2–14 % in the concentration range 0.5–10 μg L−1 were obtained in oranges, lemons, grapefruit, pears, plums, lettuces and tomatoes. The results demonstrated that the extracts of all the samples can be analyzed by the detectors used since no interfering co-extracted compounds were detected.
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    URL: http://dx.doi.org/10.1007/BF02267805
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    Modelling of GC and HPLC separations of simazin and atrazin by Experimental Design methodology (1995)
    Springer
    Chromatographia 41 (1995), S. 553-560 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gas chromatography ; Experimental design ; Modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Experimental Design methodology allows the modelling and optimization of the chromatographic separation of similar pesticides (triazine family) by GC and HPLC. The GC separation of simazin and atrazin is well modelled by a first degree equation, involving injected volume, carrier gas pressure and rising oven temperature. The LC is modelled by a second degree equation, depending on injected volume, eluent flow and composition. These calculated models allow easy optimization of the separations, using isoresponse curves.
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    URL: http://dx.doi.org/10.1007/BF02269719
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    A comparison of the critical parameters of some adsorbents employed in trapping and thermal desorption of organic pollutants (1995)
    Springer
    Chromatographia 41 (1995), S. 599-604 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Organic volatile pollutants ; Adsorbents ; Breakthrough volumes ; Thermal desorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A comparison of some adsorbents, commonly used for trapping trace volatile organic pollutants followed by thermal desorption, is presented. The evaluation has been performed on 12 compounds representative of the main classes of organic substances. Breakthrough volumes and desorption recoveries have been measured. Every adsorbent gave good results for a range of compounds, but none were able to cover all the compounds examined. Thus, a multilayer trap utilising the best features of each adsorbent was introduced with very good results.
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    URL: http://dx.doi.org/10.1007/BF02269726
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    A study of the surface modification of alumina for GC (1996)
    Springer
    Chromatographia 42 (1996), S. 77-82 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Modified alumina ; Coal mine air ; Alkenes, alkanes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A gas chromatographic method for the separation of alkanes and alkenes present in coal mine air has been developed using modified alumina columns. The separation was carried out using a GC equipped with a gas sampling valve, a FID and a surface modified alumina packed column with helium as carrier gas. An investigation was carried out into the effects of surface modifiers on alumina. The study examined the change in retention properties on alumina modified by alkali metal salts and the specific effects of the halide anions and metal cations. The paper describes the preparation of the alumina columns and the effects on selectivity of post heating the stationary phase. The study demonstrated that alumina modified with 2% sodium chloride and post heated to 150°C was the most appropriate stationary phase.
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    URL: http://dx.doi.org/10.1007/BF02271059
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    Detection of organophosphate pesticides in human body fluids by headspace solid-phase microextraction (SPME) and capillary gas chromatography with nitrogen-phosphorus detection (1996)
    Springer
    Chromatographia 42 (1996), S. 135-140 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace sampling ; Solid-phase microextraction (SPME) ; Nitrogen-phosphorus detection (NPD) ; Organophosphate pesticides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Organosphosphate pesticides have been found extractable by headspace solid-phase microextraction (SPME), and the best conditions of their extraction from human whole blood and urine samples have been investigated. The body fluid samples containing nine pesticides (IBP, methyl parathion, fenitrothion, malathion, fenthion, isoxathion, ethion, EPN and phosalone) were heated at 100°C in a septum-capped vial in the presence of various combinations of acid and salts, and SPME fiber was exposed to the headspace of the vial to allow adsorption of the pesticides before capillary gas chromatography (GC) with nitrogen-phosphorus detection. The heating with distilled water/HCl/(NH4)2SO4/NaCl and with distilled water/HCl gave the best results for urine and whole blood, respectively. Recoveries of the nine pesticides were 0.8–10.6% except for phosalone (0.03%) for whole blood, and 3.8–40.2% for urine. The calibration curves for the pesticides showed linearity in the range of 50–400 ng/0.5 mL for whole blood except for malathion (100–400 ng/0.5 mL whole blood) and 7.5–120 ng/0.5 mL for urine except for phosalone (15–120 ng/0.5 mL urine) with detection limits of 2.2–40 ng/0.5 mL for whole blood and 0.8–12 ng/0.5 mL for urine.
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    URL: http://dx.doi.org/10.1007/BF02269642
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    Complete separation of ephedrines by graphite-layer open-tubular (GLOT) column (1996)
    Springer
    Chromatographia 42 (1996), S. 309-312 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Graphite coated capillary columns ; Ephedrines separation ; Drug analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation of graphite-layer capillary column is described together with their application to the analysis of aliphatic and aromatic amines. Attention is mainly focused on the separation of ephedrines which, being sympathomimetic amines, are often present in pharmaceutical preparations, but are also illegally used by athletes as stimulants. Complete separation of these compounds, using direct GC-NPD analysis of human urine extract, without derivatisation, has been obtained.
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    URL: http://dx.doi.org/10.1007/BF02290315
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    Gas and liquid chromatography and enzyme linked immuno sorbent assay in pesticide monitoring of surface water from the western mediterranean (Comunidad Valenciana, Spain) (1996)
    Springer
    Chromatographia 42 (1996), S. 151-158 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Column liquid chromatography ; Pesticide residues ; Surface water analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A monitoring programme based on gas chromatography (NPD, ECD) using MSD for confirmatory purposes and coupled-column liquid chromatography was applied to the analysis of pesticide residues in surface water from a predominantly agricultural area of Spain (Comunidad Valenciana). Samples analysed by means of enzyme-linked immunosorbent assay gave similar results to those obtained by GC (MSD) for the determination of total triazines. The test employed had the advantages of a simple test procedure, short analysis time and high confirmatory value. Nevertheless, the multiresidue character, accuracy and unequivocal identification of individual pesticide residues of GC (MSD) make this technique the most appropriate for environmental monitoring programmes. In this monitoring programme about 200 samples were analysed between 1993–1994. 27 different pesticides were detected in 91 of these samples. The pesticides more frequently detected were dimethoate, methidathion, endosulfan A and B, endosulfan sulphate and pirimicarb. The highest concentrations found were 39.9 μg L−1 of dimethoate, 10.6 of pirimicarb and 10.6 of methidathion.
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    URL: http://dx.doi.org/10.1007/BF02269645
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    Simultaneous extraction of norflurazon and oxadixyl residues from food crops with supercritical carbon dioxide (1996)
    Springer
    Chromatographia 42 (1996), S. 147-150 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Supercritical fluid extraction ; Pesticide residues ; Norflurazon residues ; Oxadixyl residues ; Food crops
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Norflurazon and Oxadixyl residues have been analysed by HRGC-ECD after extraction from field-treated sugar cane and grapes using classical solid-liquid extraction or supercritical fluid extraction. The extraction techniques were compared; the results indicate the advantages of SFE as an alternative method for analysis of pesticides in these samples.
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    URL: http://dx.doi.org/10.1007/BF02269644
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    Fast and effective sample preparation for determination of organochlorine compounds in fatty tissue of marine mammals using microwave extraction (1996)
    Springer
    Chromatographia 42 (1996), S. 300-304 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Microwave extraction ; Sample clean-up ; Organochlorine compounds ; Blubber of marine mammals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid and effective method is described for the extraction of organochlorine compounds (PCB 153, PCB 138, PCB 180, p,p′-DDE, α-HCH, γ-HCH, ε-HCH and HCB) from seal blubber and pork fat withn-hexane using a microwave technique. Heating of the non-polarn-hexane was achieved using a microwave transformer. The lipid content of the samples obtained by this extraction was identical to that by Soxhlet extraction. After separation of sample matrix and organochlorines on a silica gel column the organochlorine compounds were determined by GC-ECD. The efficiency of the method was tested with 500 mg spiked fat, extracted using various numbers of extraction cycles. Recoveries of organochlorine compounds in grey seal blubber and spiked pork fat generally exceeded 90 %.
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    URL: http://dx.doi.org/10.1007/BF02290313
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    Determination of chloroethenes in environmental biological samples using gas chromatography coupled with solid phase micro extraction (1996)
    Springer
    Chromatographia 42 (1996), S. 313-317 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid phase micro extraction ; Chloroethenes ; Reductive dechlorination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An analytical method has been developed to determine the chloroethene series, tetrachloroethene (PCE), trichloroethene (TCE),cisdichloroethene (cis-DCE) andtransdichloroethene (trans-DCE) in environmental biotreatment studies using gas chromatography coupled with a solid phase micro extraction (SPME) technique. The volatile chlorinated compounds in aqueous solution can be analyzed directly without solvent extraction, purge and trap, or thermal heating. The calibration curves have demonstrated good linear relationships within 50.0 to 3000.0 μg L−1 concentration range. Detection limits are 18.0, 5.0, 25.0, and 42.0 μg L−1, for PCE, TCE,cis-DCE andtrans-DCE, respectively. Factors which affect the SPME process, such as sample adsorption time, thermal desorption time, and concentration of salt in the matrix, have also been evaluated.
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    URL: http://dx.doi.org/10.1007/BF02290316
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    Extraction of local anaesthetics from human blood by direct immersion-solid phase micro extraction (SPME) (1996)
    Springer
    Chromatographia 43 (1996), S. 59-62 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Local anaesthetics ; Solid phase micro extraction (SPME) ; Direct immersion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Local anaesthetics have been shown to be extractable from human whole blood samples by direct immersion (DI)-solid phase micro extraction (SPME). After deproteinization with perchloric acid, the pH of the clear supernatants of human whole blood samples containing the drugs were adjusted to about 7 with 10 M NaOH in the presence of NaCl; a polydimethylsiloxanecoated SPME fiber was then immersed directly into the sample solution to allow adsorption of the drugs before capillary gas chromatography (GC) with flame ionization detection. The DI-SPME for 1-mL whole blood gave peaks for all the drugs; only a small amount of background noise appeared and this gave no problems in the detection of the drugs. Recoveries of the ten drugs from human whole blood was 0.74–19.7 %. The calibration curves for seven drugs showed linearity in the range of 0.25–12 μg mL−1 whole blood, with detection limits of 54–158 ng mL−1.
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    URL: http://dx.doi.org/10.1007/BF02272822
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    Investigation into the separation of achiral and chiral molecules on fused-silica capillary columns coated with three peralkylated cyclodextrins (1996)
    Springer
    Chromatographia 43 (1996), S. 628-632 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Stationary phase ; β-Cyclodextrin ; Separation mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Three peralkylated β-cyclodextrins (CD), perethylated β-CD, perbutylated β-CD and peroctylated β-CD have been coated on to untreated fused-silica capillary tubing and used to separate some achiral and chiral compounds. The separation mechanism is discussed in the paper.
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    URL: http://dx.doi.org/10.1007/BF02292979
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    GC-ECD evaluation of dicofol toxicity to tropicalAstyanax bimaculatus schubarti (1996)
    Springer
    Chromatographia 43 (1996), S. 663-667 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Dicofol ; Fish ; Lethal concentration ; Bioconcentration factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Evaluation of the toxicity of Dicofol was carried out onAstyanax bimaculatus schubarti, a characteristic fish species living in tropical rivers and lakes. Experiments were under laboratory controlled conditions with atmospheric air flow and dilution water at 25°C in the static mode. Fish samples were collected and submitted to appropriate analytical procedure: Soxhlet extraction, clean-up by Florisil adsorbent and finally quantification by GC-ECD. The results showed good recoveries (〉 89%) for the developed method both in water and fish samples. The lethal concentration, LC50, and the bioconcentration factor, BCF, were 18.13 mg L−1 and 241.70, respectively forAstyanax bimaculatus schubarti demonstrating the lipophilic nature of the studied compound.
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    URL: http://dx.doi.org/10.1007/BF02292985
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    Electronic pressure control of gas chromatography-mass spectrometry for the confirmation of pesticide residues in cereals and related products (1996)
    Springer
    Chromatographia 43 (1996), S. 177-180 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Electronic pressure control ; Mass selective detector ; Pesticide residues ; Cereals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An analytical method for the confirmation of 30 pesticide residues in cereals and related products has been developed. Splitless injection with electronic pressure control using constant carrier gas flow gives higher sensitivity and better resolution than electronic pressure control and isobaric analysis. The use of electronic pressure control assures consistent retention times enabling selected ions to be collected in short time windows. Mass spectrometric detection in the selected ion monitoring mode using three ions for each pesticide ensured good sensitivity and accurate pesticide confirmation.
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    URL: http://dx.doi.org/10.1007/BF02292947
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    Gas chromatographic separation of expoxystyrenes on carbowax 20 M capillary column (1996)
    Springer
    Chromatographia 43 (1996), S. 208-210 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Epoxystyrenes ; Retention index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of some epoxystyrenes on fused silica capillary columns coated with poly(ethylene glycol) was investigated, Retention indices were determined at two temperatures to interpret chromatographic behaviour, The standard deviation was 0.3 index units.
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    URL: http://dx.doi.org/10.1007/BF02292953
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    Microwave assisted solvent extraction (MASE) for the efficient determination of triazines in soil samples with aged residues (1996)
    Springer
    Chromatographia 43 (1996), S. 527-532 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Microwave-assistend solvent extraction (MASE) ; Pesticide residue analysis ; Triazine herbicides ; Soil samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of microwave-assisted solvent extraction (MASE) as an alternative for conventional solvent extraction procedures for the determination of some triazine herbicides in soil samples has been investigated. In this study MASE method development was focused on the selection of a suitable extraction solvent prior to the instrumental analysis of uncleaned extracts with gas chromatography and nitrogen-specific detection. A mixture of dichloromethane-methanol (90∶10, v/v) yielded recoveries ranging from 89 to 103 (spiked level 200 μg/kg) with RSDs ranging from 2.1 to 5.3%. This solvent mixture is also very convenient for further procedure. The selected MASE procedure was tested by analyzing freshly spiked soil samples and samples with aged residues of atrazine, desethylatrazine, desisopropylatrazine and simazine. The results were compared with those obtained by a conventional liquid extraction method. The comparative study indicated that MASE yields recoveries at least as good as those obtained by the conventional method. Moreover, the MASE procedure provides low solvent consumption in combination with a high sample throughput.
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    Determination of fosfomycin in human urine by capillary gas chromatography: Application to clinical pharmacokinetic studies (1996)
    Springer
    Chromatographia 43 (1996), S. 293-295 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Fosfomycin in urine ; Pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A capillary gas chromatographic method for the determination of fosfomycin in human urine is described. After dilution of the sample and derivatization, analysis was on a HP-1 capillary column and a flame ionization detector was used to determine the bistrimethylsilyl derivative of fosfomycin. Response was linear in the range 50–5000 μg mL−1. The detection limit was about 10 μg mL−1. The within and between day coefficients of variation did not exceed 6%. The method was applied to the determination of fosfomycin in urine samples collected during clinical pharmacokinetic studies.
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    Thermodynamic properties of alkylbenzenes from retention-boiling point correlations in gas chromatography (1997)
    Springer
    Chromatographia 44 (1997), S. 179-186 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention-boiling point correlation ; Trouton's rule ; Alkylbenzenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A thermodynamic interpretation of the empirical correlation between retention and boiling point for alkylbenzenes in stationary phases of low and medium polarity has been found. The transfer of molecules between the liquid and mobile phases was assumed to be similar to, although not identical with, vaporization of any given pure liquid and characterized using the Trouton's rule. The two equations developed relate relative retentions to solute boiling point and two systems constants under a given set of conditions. The first equation was found to give a better description since it involves fewer assumptions and approximations. Validity of the model was confirmed by agreement between theoretical and experimental values for equation constants although the agreement becomes poorer as the stationary phase polarity increases. The relationships discussed are applicable to all congeneric solutes of low polarity in stationary phases of medium polarity.
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    Gas chromatography with flame ionization and flameless sulfur chemiluminescence detectors in series for dual channel detection of sulfur compounds (1996)
    Springer
    Chromatographia 43 (1996), S. 522-526 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Sulfur chemiluminescence detector ; Flame ionisation ; Dual-channel detection ; Optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The dual-channel detection of samples with detectors coupled in series is possible only when the first detector is a non-destructive one. However, the configuration where a destructive detector, such as the flame ionization detector (FID), is followed by the flameless, sulfur chemiluminescence detector (flameless SCD) can be used to detect simultaneously carbon and sulfur. In this work, the FID and flameless SCD are coupled in series for dual-channel detection of sulfur compounds in three gasoline samples. Optimum conditions for flameless SCD were evaluated by altering the flow rates of hydrogen and air and the oxygen pressure to the ozone generator. Samples are identified by retention indices where the homologous n-alkylthiols are used as standards. The increment in retention index per carbon number of the n-alkylthiols is 105.54 in the Quadrex 007 series, 0.32 mm i.d., 4 μm film, column.
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    Consequence of diluting modified β-cyclodextrins in a side-chain crown ether polysiloxane and in a side-chain liquid-crystalline polysiloxane-containing crown ether as stationary phases in capillary gas chromatography (1996)
    Springer
    Chromatographia 43 (1996), S. 546-550 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Stationary phase ; Polysiloxane matrices ; β-Cyclodextrin ; Crown ether ; Liquid crystal ; Coordination effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper investigates the possibility of using a sidechain crown ether polysiloxane (PDB-14-C4) and a side-chain liquid-crystalline polysiloxane-containing crown ether (PSC-3) as matrices for peralkylated β-CD employed as stationary phases. Three columns, coated with PSC-3 + permethylated β-CD, PDB-14-C4 + permethylated β-CD and PDB-14-C4 + perethylated β-CD were characterized by gas chromatography. The column efficiencies, phase transitions, and selectivities were measured and compared.
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    Direct solid-phase microextraction combined with gas and liquid chromatography for the determination of lidocaine in human urine (1998)
    Springer
    Chromatographia 47 (1998), S. 678-684 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Column liquid chromatography ; Solid-phase microextraction ; Local anaesthetic lidocaine ; Optimisation of extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Solid-phase microextraction (SPME) has been combined with gas chromatography (GC) and liquid chromatography (LC) for the determination of lidocaine in human urine. A polydimethylsiloxane (PDMS) coated fibre was directly immersed into buffered urine. Extraction conditions such as time, pH, ionic strength, temperature, and agitation were optimised. The extracted lidocaine was thermally desorbed in a split/splitless injector for analysis with a GC-FID system or desorbed with liquid in a specially designed SPME-LC interface for analysis with an LC-UV system. After optimisation the method developed was evaluated and validated. Extraction yields of 22% were obtained in about 45 min. The reproducibility of the method is 〈5% (relative standard deviation). For five-times diluted urine, linear ranges were found from 5–1000 and 25–1000 ng·mL−1 for SPME-GC and SPME-LC, with detection limits of 5 ng·mL−1 for SPME-GC and 25 ng·mL−1 for SPME-LC. SPME can be used as a simple sample pretreatment method for the determination of lidocaine in urine by GC and LC.
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    URL: http://dx.doi.org/10.1007/BF02467453
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    Investigation on five novel substituted β-cyclodextrins used as GC stationary phases (1998)
    Springer
    Chromatographia 47 (1998), S. 557-564 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Stationary phases ; β-Cyclodextrin derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Five β-cyclodextrin derivatives, heptakis[2,6-di-O-pentyl-3-O-(4-nitrobenzyl)-β-CD (CD-I), heptakis [2,6-di-O-pentyl-3-O-(5-hexenyl)]-β-CD (CD-II), heptakis-(2, 6-di-O-cinnamyl-3-O-methyl)-β-CD (CD-III), heptakis-(2, 6-di-O-cinnamyl-3-O-acetyl)-β-CD (CD-IV) and heptakis(2, 6-di-O-cinnamyl-3-O-trifluoroacetyl)-β-CD (CD-V), were synthesized and coated on fused-silica capillary coluns. Their chromatographic characteristics were tested and compared with heptakis (2,3,6-tri-O-pentyl)-β-CD (CD-VI) and heptakis (2,6-di-O-pentyl-3-O-trifluoroacetyl)-β-CD (CD-VII). It was found that the size, polarity, and aromatic property of the substituted group at the 3-position of heptakis (2,6-di-O-pentyl)-β-cyclodextrins greatly influenced their chromatographic properties and separation ability. The introduction of aromatic group or a group containing a double-bond may bring π-π interactions between the host and guest molecules, and therefore increased the separation ability of the β-CDs for substituted benzene isomers. Introduction of cinnamyl groups in to the 2,6-3-position of β-CD has a significant effect on the chromatographic properties of the stationary phases(CD-III-CD-V).
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    URL: http://dx.doi.org/10.1007/BF02467495
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    Determination of heats of vaporization and gibbs free energies of alkylbenzenes on GC stationary phases of different polarity (1998)
    Springer
    Chromatographia 48 (1998), S. 89-94 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Heats of vaporization ; Gibbs free energies ; Kováts retention indices ; Alkylbenzenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In our paper we propose a new method for the determination of heats of vaporization (ΔH vap(i)) and the Gibbs free energies of vaporization (Δμp(i)) for individually selected alkylbenzenes, chromatographed on stationary phases of low and medium polarity. The method is based on a new thermodynamic description of the Kováts retention index (I (i)) making use of Trouton's rule. In fact, we attribute physical significance to two empirical relationships, well known from the literature. We can describe thermodynamically the magnitude ofI (i) using two relations, each of them potentially useful for further determination of δH vap(i) and Δμp(i). A comparison was made of the results obtained with the use of our new approach and of those already existing in the literature attained in a completely different way. The comparison suggests that the calculated δH vap(i) and Δμp(i) values are thermodynamically acceptable and hence correct, and the data suit into the series of similar values determined on stationary phases of different polarity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467523
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  • 92
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    Separation of polychlorinated biphenyls from chlorinated pesticides using aminopropyl bonded-phase cartridge and determination by GC-ECD (1998)
    Springer
    Chromatographia 48 (1998), S. 293-298 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid phase extraction ; Polychlorobiphenyls ; Clorinated pesticides ; Organochlorine separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gas chromatography of polychlorinated biphenyls and chlorinated pesticides in water samples is carried out after adsorption from a 25–500 mL sample, on a cartridge containing 100 mg aminopropyl-bonded porous silica. The clean-up step in which the PCBs and chlorinated pesticides are separated in different eluates is achieved by passing 25 mL of 40% aqueous methanol through the NH2 Sep-Pak cartridge. The PCBs are desorbed with 500 μL ethylacetate, which is concentrated and analysis by GC-ECD. The average recovery, at 1 ppb is 〉97% with a standard deviation 〈2. The limits of detection are 0.1 ng μL−1 and 5 pg μL−1 respectively for Cl3-PCB and Cl8-PCB congeners. In the separation of PCBs from the chlorinated pesticides tested in this work, only the Aldrin is adsorbed for 60% with the PCBs by the NH2 Sep-Pak cartridge. The method described is rapid, simple and reproducible.
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    URL: http://dx.doi.org/10.1007/BF02467685
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    Characterisation of GC stationary phases in multilinear retention model (1998)
    Springer
    Chromatographia 48 (1998), S. 728-738 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Stationary phases ; Prototypical phases ; Retention model ; Retention value ; Dipolarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Stationary phases are characterised in a multilinear retention model by retention data of a set of selected prototypical substances. Prototypical stationary phases confirm the application of prototypical substances in the retention model. For comparison, 27 stationary phases are characterized with solute descriptors of the solvation model. New adjusted substance factors are calculated for 33 selected compounds for a new characterization of GC stationary phases in the extended retention model with retention values, calculated from retention indices and b-values of the n-alkane equation. Substance dipolarityD N-factors are separated from πN, the adjusted dipolarity-polarisability. New substance factors give satisfying correlation results and new explanatory factors as phase descriptors for 27 stationary phases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467640
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    Precision of milk fat quantitation in mixed fats by analysis of butyric acid (1998)
    Springer
    Chromatographia 48 (1998), S. 758-762 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Butyric acid ; Milk fat content ; Mixed fats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Quantitation of the milk fat content in mixed fats is of interest in food analysis. It can be achieved by calculation from the butyric acid (C4) content in the mixed fat and a mean C4 content for pure milk fats. Alternatively, instead of applying a C4 mean value, the C4 content in the actual milk fat can be used if this reference sample is available. A recently improved analytical method based on gas chromatography of butyric acid methyl ester using an internal standard has been applied to determine the milk fat content in mixtures with beef tallow, lard, soybean oil, olive oil, sunflower oil, palm kernel oil and palm oil ranging from 1 to 90% milk fat content. Within the whole range of mixtures, mean absolute deviations between the determined and the actual milk fat content were below 0.5% and the maximum absolute deviation was not more than 1.0% when using the reference sample. The overall mean absolute deviation was 0.04% for milk fat contents of 1 to 10% and 0.28% for milk fat contents of 10 to 90%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467644
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    Determination of acids in Brazilian sugar cane spirits and other alcoholic beverages by HRGC-SPE (1998)
    Springer
    Chromatographia 48 (1998), S. 751-757 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid phase extraction ; Brazilian sugar cane spirit ; Lower fatty acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A gas chromatographic method for the analysis of seventeen acids in a water/ethanol matrix is described. The diluted samples were first concentrated by solid phase extraction. Nonanoic acid was the internal standard. A good separation profile was obtained for all compounds, including the isomers: n and iso-butyric acids, n and isovaleric acids and n and iso-caproic acids. The method is fast, sensitive (20–30 μg L−1) and has a good reproducibility (4–7 %). The recovery was in the range of 94%–116% for the medium chain acids (C7-C16). This method allowed the identification of fourteen acids in caninhas and other spirits. The total acid content and the profile of the exportation type caninhas are similar to the ones obtained for several international beverages.
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    URL: http://dx.doi.org/10.1007/BF02467643
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    Gas chromatography with UV-vis molecular absorption spectrometry detection: Increasing sensitivity of the determination of alcohols and phenols by derivatization (1998)
    Springer
    Chromatographia 48 (1998), S. 542-547 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; UV-Vis detection ; Gas phase absorption spectrometry ; Derivatization ; Alcohols and phenols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is proposed for the determination of alcohols and phenols based on their derivatization to benzoates and gas chromatography-gas phase molecular absorption spectrometry. All parameters affecting the derivatization reaction, such as the solvent, basic medium, benzoyl chloride and stirring time, were optimized. Chromatographic and instrumental conditions were also studied. Finally, a calibration study was performed and the results were compared to that obtained by the direct determination of the compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466647
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    Gas chromatography analysis of organophosphorous pesticides in plant samples (1998)
    Springer
    Chromatographia 48 (1998), S. 156-157 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Gel permeation chromatography ; Organophosphorous pesticides ; Plant samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The work presents a GC method for the determination of six organophosphorous pesticide residues in cabbage. Chopped cabbage was blended with acetone, then extracted with the mixture of n-hexane:methylene chloride (1:1). The extract was purified on a GPC column packed with BioBeads SX-3 gel. The pesticides were eluted with the mixture of methylene chloride:cyclohexane (1:1) at the flow rate of 0.5 mL min−1. After concentrating the extract was analysed by GC. Nearly 100 samples of cabbage were analysed; trace residues of dimethoate (about 0.05 ppm) were found in 10 samples. The average recoveries of the pesticides were above 80% with a relative standard deviation mostly less than 10%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467534
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    Gas chromatographic determination of major sterols in edible oils and fats using solid-phase extraction in sample preparation (1998)
    Springer
    Chromatographia 48 (1998), S. 745-750 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid-phase extraction ; Rapeseed oil ; Sterols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A capillary gas chromatographic method is described for the determination of major plant sterols and cholesterol in edible oils and fats. In the sample preparation procedure reversed-phase, solid-phase extraction with C18 adsorbent was used to extract the unsaponifiable matter and for sample cleanup after saponification. Sterols were quantitated as their trimethylsilylether derivatives using an internal standard method (betulin). The method was validated by recovery tests and analysis of two reference materials representing vegetable oil mixture and milk fat matrices. Average recoveries of spiked cholesterol and cholesterol acetate in rapeseed oil were 103±4% (n=12) and 101±3% (n=10), respectively. The sterol values determined in the reference materials were found to be in a good agreement with their given certified or indicative values. Applied to edible oils and fats, plant sterols and cholesterol at levels〉20 mg kg−1 could be accuratively quantitated.
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    URL: http://dx.doi.org/10.1007/BF02467642
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    Headspace gas chromatography analysis of toxic contaminants in ethoxylated alcohols and alkylamines (1998)
    Springer
    Chromatographia 48 (1998), S. 299-304 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace sampling ; Ethoxylated alcohols ; Ethoxylated alkylamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Headspace-gas chromatography was used to determine the contents of toxic 1,4-dioxane, ethylene oxide and ethylene glycol in ethoxylated alcohols and alkylamines, and in commercial cosmetics and washing products. A Permaphase PEG capillary column was used for the determination of 1,4-dioxane and ethylene oxide and a DB-17 column for ethylene glycol determination. Dimethylformamide was used as the solvent in the determination of 1,4-dioxane and ethylene oxide, and undecanol in the case of ethylene glycol. The detection limits for ethylene oxide, 1,4-dioxane and ethylene glycol are 1,2 and 10 μg·g−1, respectively.
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    URL: http://dx.doi.org/10.1007/BF02467686
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    [60] Fulleropyrrolidine functionalized polysiloxane as a stationary phase for capillary gas chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 293-298 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; [60] Fulleropyrrolidine polysiloxane ; High temperature stationary phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In this paper, a new type of [60]fulleropyrrolidine functionalized polysiloxane in which the fullerene moieties were incorporated in the main polysiloxane chain was synthesized the first time and used as a stationary phase for capillary gas chromatography. It demonstrated high column efficiency (2600–2866 plates m−1, on a 250 μm diameter column, for naphthalenek=3.1–3.2, 120 °C), a wide operational temperature range (90–360 °C) and outstanding thermostability. It can be used at 360 °C with a baseline drift of 5∼8×10−15A. Benzene homologues, aromatic hydrocarbons, polar compounds such as alcohols, esters, ketones, anilines and phthalic diesters can be seperated well on this column.
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    URL: http://dx.doi.org/10.1007/BF02467559
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