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  • Column liquid chromatography
  • Gas chromatography
  • Springer  (56)
  • National Academy of Sciences
  • Periodicals Archive Online (PAO)
  • 1995-1999  (56)
  • 1985-1989
  • 1980-1984
  • 1999  (56)
Collection
Keywords
Publisher
  • Springer  (56)
  • National Academy of Sciences
  • Periodicals Archive Online (PAO)
  • Wiley-Blackwell  (6)
Years
  • 1995-1999  (56)
  • 1985-1989
  • 1980-1984
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  • 1
    Electronic Resource
    Electronic Resource
    Monitoring of nicotine in air using sorptive enrichment on polydimethylsiloxane and TD-CGC-NPD (1999)
    Springer
    Chromatographia 49 (1999), S. 520-524 
    Details
    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%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467752
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of ochratoxin a in beer by high-performance liquid chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 543-546 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; MS-MS detection ; Electrospray-Ionization (ESI) ; Beer ; Ochratoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Ochratoxin A (OTA) is a nephrotoxic and nephrocacinogenic mycotoxin commonly produced by several ubiquitousAspergillus andPenicillium species. OTA is found predominantly in cereals and derived products, and therefore OTA may be transferred into beer from contaminated grain. Thirty-five samples of German beers were analyzed: OTA was extracted with toluene and purified by solid phase extraction using silica cartridges. OTA was determined by high-performance liquid chromatography with fluorescence detection. Since of fluorescence detection is not specific in this instance, the beer samples were also analyzed by high-performance liquid chromatography electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS). OTA levels in the range of 0.1–0.2 μg L−1 were found in 9 beer samples, 21 samples contained trace amounts of OTA (〈0.1 μg L−1) and in 5 samples no OTA was detectable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467756
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  • 3
    Electronic Resource
    Electronic Resource
    Analysis of doxorubicin in cell culture media and human plasma using solid phase extraction and HPLC (1999)
    Springer
    Chromatographia 49 (1999), S. 557-561 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solid phase extraction ; Doxorubicin ; Cell culture media ; Human plasma ; Fluorescence detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Doxorubicin is an antineoplastic antibiotic isolated fromStreptomyces peucetius var.cesius clinically used in the treatment of tumors such as lung or breast, Hodgkin's disease and various types of leukemias. The main goal of this study was to develop a simple and sensitive HPLC method with fluorescence detection for the quantitation of doxorubicin in cell culture media collected during an in vitro studies and in human plasma. Solid phase extraction (C2 silica) was applied. The experiment established five-point standard curve (1 ng mL−1 to 100 ng mL−1). The standard curves prepared in blank cell tissue media were linear over the range of doxorubicin assayed and had a mean correlation coefficient of 0.9973±9.43×10−4 and slope 0.02545±1.85×10−3. The standard curves prepared in human plasma were linear and had mean correlation coefficient of 0.997 and slope 0.01885±5.19×10−4. The limit of quantitation for doxorubicin in both specimens was arbitrarily established to be 1 ng mL−1. Intra-day variabilities were determined using 3–4 replicates of control solutions of doxorubicin (3 ng mL−1 and 30 ng mL−1) in blank plasma and cell culture media. Inter-day variabilities were determined over a four day period analyzing replicates of controls. All precision and accuracy values fell within the acceptable range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467759
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  • 4
    Electronic Resource
    Electronic Resource
    Separation of human serum albumin components by RP-HPLC and CZE and their characterization by ESI-MS (1999)
    Springer
    Chromatographia 49 (1999), S. S21 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Capillary zone electrophoresis ; Electrospray ionization-mass spectrometry ; Human serum albumin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Human serum albumin (HSA) is one of the most abundant human proteins and has been shown to be heterogeneous. A RP-HPLC method has been developed to separate HSA components in commercially available preparations. Separations were carried out on Aquapore RP-300, C8 columns using gradient elution with a combination of acetonitrile/water mobile phases containing 0.05% trifluoroacetic acid as ion-pairing agent. Optimum resolution was attained on narrow-bore columns using a stepwise, linear gradient that incorporated a shallow intermediate step of 0.20%/min in Mobile Phase B. Under similar elution conditions, separations carried out on standard-size columns showed the expected decrease in resolution due to increased peak widths. A comparative analysis of three commercial products highlighted qualitative and quantitative differences. Capillary zone electrophoresis was used for the analysis of collected RP-HPLC fractions. Results indicated that while the HPLC separation was incomplete, one of the major HPLC peaks was primarily composed of one of the three main components typically separated by CZE. ESI-MS was used to characterize the two major RP-HPLC fractions and also showed that the HPLC separation was incomplete. The MaxEnt transform of the HPLC peaks was consistent with components all being HSA and closely related derivatives.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02468972
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  • 5
    Electronic Resource
    Electronic Resource
    [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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467559
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  • 6
    Electronic Resource
    Electronic Resource
    FMOC-Cl as derivatizing agent for the analysis of amino acids and dipeptides by the absolute analysis method (1999)
    Springer
    Chromatographia 49 (1999), S. 317-320 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amino acids ; FMOC derivatives ; Oligopeptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary One classical method for quantitation of amino acids in proteins is hydrolysis of the proteins and determination of the free amino acids. Although the drastic experimental conditions necessary for complete hydrolysis always cause degradation of some of the amino acids, if mild hydrolysis conditions are used, a mixture of amino acids and oligopeptides is obtained. If these conditions are adequately tuned, the oligopeptides are almost exclusively dipeptides. For this reason we have initiated a study to find a derivatizing agent suitable for the analysis of amino acids and dipeptides by an absolute method of quantitation already tested for amino acids. FMOC-Cl was found to be a suitable derivatizing agent for this purpose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467563
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  • 7
    Electronic Resource
    Electronic Resource
    Peak capacity in packed capillary column solvating gas chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 333-337 
    Details
    ISSN: 1612-1112
    Keywords: Supercritical fluid chromatography ; Gas chromatography ; Solvating gas chromatography ; Peak capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In this paper, a general peak capacity expression was evaluated using columns containing various packing materials under solvating gas chromatography (SGC) conditions. Differing from column efficiency, peak capacity can describe both separation capability and speed when introducing the dead time into the peak capacity expression. Various factors that influence peak capacity in SGC are described, including particle pore size, chemical surface modification, particle size, column length, temperature, and pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467566
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  • 8
    Electronic Resource
    Electronic Resource
    High-performance liquid chromatographic determination/identification of oxytetracycline and sulphadimidine in meat and eggs (1999)
    Springer
    Chromatographia 49 (1999), S. 369-373 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Sep-Pak CN cartridge ; Oxytetracycline ; Sulphadimidine ; Meat and eggs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid method for the simultaneous determination/identification of residual oxytetracycline (OTC) and sulphadimidine (SDD) in meats (beef, pork, chicken) and eggs by high-performance liquid chromatography (HPLC) was developed. The extraction of OTC and SDD was performed using a Sep-Pak® CN cartridge. The extracts contained OTC/SDD analytes when examined by HPLC using a LiChrospher® 100 RP-8 end-capped column and a mobile phase of acetonitrile-acetic acid-water (28:4:68, v/v/v) with a photodiode array detector. The average recoveries from spiked samples (0.1 μg g−1 and 1.0 μg g−1) were in excess of 80.2% with coefficients of variation between 1.5 and 5.0%. The limits of detection for OTC and SDD were 0.05 and 0.02 μg g−1, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467608
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  • 9
    Electronic Resource
    Electronic Resource
    Improved separation of polyethylene glycols widely differing in molecular weight range by reversed-phase high performance liquid chromatography and evaporative light scattering detection (1999)
    Springer
    Chromatographia 49 (1999), S. 615-620 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Evaporative light-scattering detection ; MALDI-TOF ; Polyethylene glycols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polyethylene glycols (PEGs) of nominal molecular weight (M) 200, 400, 600, 1000, 1500, 3000, 4000 and 6000 were chosen as model compounds and subjected to reversed-phase high performance liquid chromatography (RP-HPLC) on an octadecasilyl silica gel (C18) stationary phase using a binary gradient composed of acetonitrile and water and evaporative light scattering detection (ELSD). Satisfactory resolution of oligomers up to M of 3000 was accomplished; the higher M samples PEG-4000 and PEG-6000 could not be further resolved into the constituent oligomers and therefore, M=4000 marks the upper limit of oligomer resolution. Despite some peak overlapping as a consequence of the more or less broad oligomer distribution, individual types of PEG samples can be distinguished from each other by their characteristic chromatographic fingerprint patterns, as shown with a mixture consisting of PEG-400, PEG-1000, PEG-3000, PEG-4000 and PEG-6000. For this reason, the method is well-suited for characterization of samples containing PEGs widely differing in M. In addition, matrix assisted laser desorption ionization time of flight mass spectroscopy (MALDI-TOF/MS) performed with PEG-600, PEG-1000 and PEG-3000 revealed that the optimum degree of oligomer resolution has been achieved by use of the present method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466902
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  • 10
    Electronic Resource
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    Separation of the enantiomers of amino and amide compounds on novel chiral stationary phases derived from a crown ether (1999)
    Springer
    Chromatographia 49 (1999), S. 621-627 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral stationary phases ; Crown ether derivatives ; Amino compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The enantiomers of primary amino compounds have previously been resolved on a chiral stationary phase (CSP) CSP-18C6I, prepared by immobilizing (+)-18-crown-6 tetracarboxylic acid. In this study related chiral stationary phases were prepared in an effort to broaden the scope of CSP18C6I. CSP-18C6II, synthesized to investigate the effect of spacer length, resolved the enantiomers of 2-amino-1,2-diphenylethanol and 1-(1-naphthyl)ethylamine (1-NEA) (hydrophobic amino compounds) with the largerk values and smaller α values than on CSP-18C6I, probably because of the greater hydrophobicity of CSP-18C6II. Use of CSP-18C6III, synthesized by modification of carboxylic acid functionality of CSP-18C6II by introduction of another chiral moiety,S-1-NEA, resulted in larger α values for 2-amino-1-phenylethanol and 2-amino-1-phenylpropanol than on CSP-18C6II, but the enantiomers of 1-NEA were not resolved, because of steric hindrance between 1-NEA and the chiral moiety. The amide derivativeN-3,5-dinitrobenzoyl-1-(α-naphthyl)ethylamine (DNN) as π-acceptor (3,5-dinitrobenzoyl function) or π-donor (naphthylethylamide function), and no primary amino functionality, was resolved on CSP-18C6III. The mechanism of separation of the enantiomers of DNN was assumed to be the π−π interaction between the 3,5-dinitrobenzoyl function (π-acceptor) of DNN and theS-1-NEA moiety (π-donor) of CSP-18C6III.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466903
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  • 11
    Electronic Resource
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    Determination of alcohols using condensation agent carbazole-9-acetyl-benzene-disulfonate by high performance liquid chromatography with pre-column fluorescence derivatization (1999)
    Springer
    Chromatographia 49 (1999), S. 657-665 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Alcohols ; Pre-column fluorescence derivatization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sensitive LC method for the determination of alcohols, using fluorescent condensation agent carbazole-9-N-acetylbenzne-disulfonate(CABS), has been developed. A mixture of alcohols and triethylamine catalyst in dichloromethane or chloroform is treated with CABS to give quantitative yields of esters. Emission maximum for the derivatized alcohols is 365 nm (λex 335 nm). The labeled derivatives are very stable, no significant decomposition is observed after heating in 40% at 40°C for 24 h. The method, in conjunction with a multigradient program, offers baseline resolution of common alcohol derivatives on a reversed-phase C18 column. Studies on derivatization conditions indicate that primary and secondary alcohols react very fast with CABS in the presence of triethylamine in dichloromethane or chloroform to give the corresponding fluorescent derivatives. This method is more convenient and more efficient than previous methods which require prior conversion of carboxylic acids to acyl chlorides. The separation of alcohol derivatives has good reproducibility and the rsd's (n=5) for 50 pmol of each alcohol are 4%. Detection limits are at the fmol level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466908
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  • 12
    Electronic Resource
    Electronic Resource
    Microwave assisted extraction and sonication of polychlorobiphenils from river sediments and risk assesment by toxic equivalency factors (1999)
    Springer
    Chromatographia 49 (1999), S. 21-27 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Microwave and ultrasonic extraction ; River sediment ; Dioxin-like polychlorobiphenyls ; Toxic equivalency factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Microwave extraction and ultrasonication of dioxin-like polychlorobiphenyls (PCBs) from sediment samples were investigated. After separation of dioxin-like PCBs from a sample matrix on an acidic-alkaline silica gel column, dioxin-like PCBs were determined by GC-ECD, using dual capillary columns. Recoveries of dioxin-like PCBs in river sediment samples exceeded 80% by both extraction techniques. Toxic equivalency factors and their use for the PCB congeners investigated were applied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467182
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  • 13
    Electronic Resource
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    Liquid chromatography of jasmonic acid amine conjugates (1999)
    Springer
    Chromatographia 49 (1999), S. 42-46 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral resolution ; Jasmonic acid ; Plant growth regulators ; Amine conjugates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Racemic jasmonic acid (3R,7R/3S,7S)-(±)-JA) was chemically conjugated with different biogenic amines originating from aliphatic and aromatic α-amino acids by decarboxylation. The resulting isomeric compounds were subjected to reversed-phase high-performance liquid chromatography (HPLC) and to HPLC on the chiral stationary phases Chiralpak AS and Nucleodex β-PM. Under reversed-phase conditions, all the homologous amine derivatives tested could be separated from each other except the JA-conjugates containing 2-phenyl-ethylamine and 3-methylbutylamine. On both chiral supports the (3R,7R)-(−)-JA conjugates eluted earlier than those of the enantiomeric counterpart (3S,7S)-(+)-JA. On Chiralpak AS all the isomers studied could be separated to baseline with a mobile phase containingn-hexane and 2-propanol. The calculated resolution factors were between 1.80 and 4.17. The pairs of isomers were also chromatographed on the cyclodextrin stationary phase Nucleodex β-PM with methanol-triethylammonium acetate buffer as mobile phase. Under these conditions resolution factors were between 0.74 and 1.29. The individual isomers were chiroptically characterized by measurement of their circular dichroism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467185
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  • 14
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    Determination of ethinylestradiol and gestodene in oral contraceptives by micellar electrokinetic chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 65-70 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micellar electrokinetic chromatography (MEKC) ; Oral contraceptives ; Ethinylestradiol ; Gestodene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A micellar electrokinetic chromatographic method is presented which permits quantification of ethinylestradiol and gestodene in pharmaceutical products. Separation was carried out at 25°C and 25 KV, using a 20 mM borate buffer (pH 9.2), 15 mM sodium dodecylsulfate in 30% acetonitrile-water (v/v). Under these conditions analyses were carried out in 7 min. Four different oral contraceptives were analysed and the results compared favourably with those of a reference liquid chromatographic method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467189
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  • 15
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    Determination of yttrium and lanthanum in zirconium dioxide by HPLC, X-ray fluorescence and neutron activation analyses (1999)
    Springer
    Chromatographia 49 (1999), S. 91-94 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Zirconium oxide ceramics ; X-ray fluorescence ; Neutron activation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Lanthania-and yttria-stabilized zirconium oxide ceramics have been examined using High Performance Liquid Chromatography (HPLC), thermal neutron activation (NA) and X-ray Fluorescence (XRF) analyses and thus determine the stabilizer content. Ceramic powders with the composition ZrO2:x mol % La2O3 (x=5, 10, 15, 20 and 33) and ZrO2:x mol % Y2O3 (x=10, 15, 20 and 25) were prepared by the citrate and the co-precipitation techniques, respectively. The lanthanum content was determined by HPLC (x=5.09, 9.78, 14.98, 19.81 and 25.94) and NA (x=5.15, 10.32, 17.25, 21.08 and 27.97) analyses, the yttrium content by HPLC (x=8.5, 13.5, 17.9 and 22.1) and XRF (x=9.9, 15.8, 20.1 and 24.9) analyses. An experimental sequence, based on continuous dilution of ceramic powder solutions, is proposed for preparing samples for HPLC measurements. A swimming pool nuclear reactor is used for NA analysis. The quantitative determinations of yttrium and lanthanum doping levels obtained using those techniques are described.
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    URL: http://dx.doi.org/10.1007/BF02467194
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  • 16
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    Stereochemical resolution of racemates, in HPLC, using a chiral stationary phase based upon immobilized α-chymotrypsin. I. Structural chiral separations (1999)
    Springer
    Chromatographia 49 (1999), S. 595-605 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; α-Chymotrypsin immobilized on silica ; In situ immobilization process ; Structural chiral separations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary α-Chymotrypsin was immobilized on an epoxide derivatized silica gel by anin situ immobilization process. Several racemates were resolved by a structural recognition mechanism. The immobilization process and the stability of this α-chymotrypsin stationary phase have been studied. The mobile phase parameters including the ionic strength, pH and the effects of organic modifiers have been also investigated. The retention, efficiency and stereoselectivity of the solutes appear to be related to their molecular structure, hydrophobicity and electrostatic interactions. These relationships determine the recognition mechanism and the position of each enantiomer in the active site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466900
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  • 17
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    Stereoselective analysis of idrapril and its stereoisomers by reversed-phase high-performance liquid chromatography on a chiral-AGP column (1999)
    Springer
    Chromatographia 49 (1999), S. 628-634 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Enantiomer separation ; Chiral-AGP column ; Idrapril ; Temperature effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A direct liquid-chromatographic method has been developed for the stereoselective analysis of idrapril and its stereoisomers on a chiral α1 glycoprotein (AGP) column. The influence of flow-rate, temperature, and mobile phase composition on retention and selectivity was evaluated to find the optimum conditions for chiral separation.
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    URL: http://dx.doi.org/10.1007/BF02466904
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  • 18
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    Preparation of branched-polyfluoroalkylsilane-coated silica gel columns and their HPLC separation characteristics (1999)
    Springer
    Chromatographia 49 (1999), S. 649-656 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polyfluoroalkyl-coated silica ; 29Si CP/MAS NMR ; Polyaromatic compounds ; Fluorinated compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The conditions for reaction of the branched polyfluoroalkylsilane D3CL with silica gel have been examined. From elemental analyses and29Si NMR spectra it was found that the surface coverage and endcapping of D3CL-coated silica gel (Fluofix®) were the same as for ODS packings. The separation behavior of these phases was compared that of a variety of other packings. For polyaromatic compounds and benzene derivatives Fluofix worked in the reversed-phase mode and its retention characteristics were similar to those of C1 or CN packings. For fluorinated compound the retention characteristics of the phases is similar to those of ODS although with MeOH-water and MeCN-water mobile phases the pressure loss was lower for the fluorinated phases than for ODS.
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    URL: http://dx.doi.org/10.1007/BF02466907
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  • 19
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    The effect of pH on the high pH anion-exchange chromatography elution of monosaccharides (1999)
    Springer
    Chromatographia 49 (1999), S. 699-702 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Anion-exchange chromatography ; High ph elvents ; Monosaccharides ; Carbopac PA-100
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary We have studied the elution behaviour of six common monosaccharides, fucose, galactosamine, glucosamine, galactose, glucose and mannose, on the CarboPac PA-100 column. The relative elution positions of galactose, glucose and mannose were dependent on the sodium hydroxide concentrations, a phenomenon which was likely to be the result of differential ionisation of the hydroxyl groups at ring positions two and four. The optimal resolution of the monosaccharides studied was achieved by elution with 30 mM sodium hydroxide with no appreciable loss in sensitivity at this low concentration.
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    URL: http://dx.doi.org/10.1007/BF02466915
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  • 20
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    High performance liquid chromatography method for the determination of meropenem in human plasma (1999)
    Springer
    Chromatographia 49 (1999), S. 253-255 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Meropenem in human plasma ; Solid phase extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper describes an HPLC method for the determination of meropenem in human plasma. The method uses solid phase extraction (SPE) of the samples and has good sensitivity, precision and accuracy. The limit of quantification in plasma samples is 0.02 μg mL−1. Calibration curves were linear over a large dynamic range, namely within 0.02–50 μg mL−1. The method was applied to the determination of meropenem levels in patients receiving meropenem, as a single dose or at steady state.
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    URL: http://dx.doi.org/10.1007/BF02467552
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  • 21
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    Conversions of carbon monoxide oxidation over Pt−Rh alloy catalysts calculated by a new gas chromatographic technique (1999)
    Springer
    Chromatographia 49 (1999), S. 285-292 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Reversed-flow gas chromatography ; Carbon monoxide oxidation ; Bimetallic Pt−Rh catalysts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Catalytic fractional conversions of carbon monoxide to carbon dioxide over Pt−Rh alloy catalysts in the presence of excess oxygen, under steady-state or non steady-state conditions, as well as corresponding rate constants for the CO oxidation reaction were measured by using the reversed-flow gas chromatographic technique. From the variation of the conversions with temperature, maximum values of conversions were found, which depend on the catalysts nature (Pt content), while from the variation of the rate constants with temperature, activation energies for the CO oxidation reaction were determined, which also depend on the catalyst Pt content. The results suggest a synergism between Pt and Rh in the Pt−Rh bimetallic catalysts in accordance with previous works, showing that reversed-flow gas chromatography can be used with simplicity and accuracy for the kinetic study of the CO oxidation reaction, which is of technological importance for the control of air pollution.
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    URL: http://dx.doi.org/10.1007/BF02467558
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    A very thick film open-tubular trap for headspace capillary gas chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 321-326 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace analysis ; Open-tubular trap ; Very thick film column
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An open-tubular trap with a very thick film was studied for “full on-line” headspace capillary gas chromatography, and was used as an enrichment trap for headspace sampling. The preparation of the open-tubular column with up to an 80 μm thick film, by combining both static and dynamic coating, is described in detail. The break-through volume for the open-tubular trap of different film thickness, as the loading capacity for HS sampling, does not increase linearly in proportion to the film thickness. A study of the difference between a packed adsorbent trap and an open-tubular trap shows that HS capillary GC with open-tubular trap loses less of the retention capacity, has better resolution ability and higher recovery. By independently and rapidly heating the open-tubular trap, the GC peaks may have higher resolution. Examples of successful analyses, by the opentubular trap with “full on-line” HS capillary GC, include trace aromatic hydrocarbon (1 ppm-100 ppm) in polybutadiene-styrene rubber and trace alcohol and acrylic esters (10 ppm–1000 ppm) in polyacrylate hydrous emulsion.
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    URL: http://dx.doi.org/10.1007/BF02467564
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    Retention system, thermodynamic properties and structure correlations of environmental analytes (1999)
    Springer
    Chromatographia 49 (1999), S. 385-390 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Structure correlations ; Polycyclic aromatic hydrocarbons ; Polychlorinated biphenyls ; Polychlorinated pesticides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A composite chromatographic retention index system has been developed for identifying polycyclic aromatic hydrocarbons, polychlorinated biphenyls and polychlorinated pesticides. When retention indices and thermodynamic data of polycyclic aromatic hydrocarbons on 5% phenylmethylsiloxane stationary phase were compared with those obtained on polydimethylsiloxane a correlation was found between retention and electronic properties. Determination and quantitation of individual contaminants in water and sediment samples from Lake Mecoacán were achieved by capillary gas chromatography with flame ionization and electrocapture detection.
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    URL: http://dx.doi.org/10.1007/BF02467611
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    Trace analysis of surfactants derived from fatty alcohols II. Hydrolysis and enrichment techniques (1999)
    Springer
    Chromatographia 49 (1999), S. 12-16 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fatty alcohol sulfates ; Alkyl polyglycosides ; Trace analysis ; Steam distillation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Acid catalyzed hydrolysis of fatty alcohol sulfates under reflux condition or by microwave heating is compared. Microwave hydrolysis turned out to be faster and more convenient to use. The combination of reflux hydrolysis of fatty alcohol sulfates or alkyl polyglycosides and the simultaneous steam distillation of the generated fatty alcohols gives a very powerful sample preparation and enrichment method for fatty alcohol sulfates and alkyl polyglycosides. The preconcentrated fatty alcohols are derivatized and detected via fluorescence detection. The applicability of the method is demonstrated by the analysis of fatty alcohol sulfates in cosmetics and in river water as matrices spiked with approximately 4 ppb fatty alcohol sulfates.
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    URL: http://dx.doi.org/10.1007/BF02467180
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    Identification and quantitation of polyphenols in leaves ofMyrtus communis L. (1999)
    Springer
    Chromatographia 49 (1999), S. 17-20 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; DAD and MS detection ; Liquid-solid extraction ; Catechin derivatives ; Myricetin derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A liquid-solid extraction and purification procedure (LSE) was developed to identify and quantify polyphenols in the leaf tissue ofMyrtus communis L. Identification and quantitation of individual compounds was performed using HPTLC, HPLC-DAD and HPLC-MS analysis. Leaves ofMyrtus communis L. contain small amounts of phenolic acids (caffeic, ellagic and gallic acids) and quercetin derivatives (quercetin 3-O-galactoside and quercetin 3-O-rhamnoside), whereas catechin derivatives (epigallocatechin, epigallocatechin 3-O-gallate, epicatechin 3-O-gallate) and myricetin derivatives (myricetin 3-O-galactoside, myricetin 3-O-rhamnoside) are present in large amounts. This is the first report on the occurrence of galloyl-derivatives of catechin and gallo-catechin inMyrtus communis L. leaves.
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    URL: http://dx.doi.org/10.1007/BF02467181
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    p-Hydroxymercuribenzoate as thiol-protein modifier for simultaneous determination of glycolytic enzymes by hydrophobic-interaction chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 47-53 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Glycolytic enzymes ; p-Hydroxymercuribenzoate ; 203Hg-labelledp-hydroxymercuribenzoate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of hydrophobic-interaction chromatography (HIC) is proposed for the simultaneous determination of more than one thiol-protein after formation of the corresponding mercury mercaptides withp-hydroxymercuribenzoate (PHMB). The new chromatographic procedure, based on the HIC separation of the modified proteins from each other and from excess organomercury reagent has been successfully applied to the quantitative determination of phosphoglucose isomerase (PGI) and phosphoglucose mutase (PGM) in crude PGI powder, and of L-lactate dehydrogenase, PGM and aldolase in crude pyruvate kinase from rabbit muscle. The suitability of203Hg-labelled PHMB has been tested in the analysis of mixtures, which give barely distinguishable UV-peaks owing to the presence of other non-thiol components in the sample. For this purpose glyceraldehyde 3-phosphate dehydrogenase (GAPDHy) and PGIy from bakers yeast have been considered. Results obtained in experiments performed by both procedures are reported.
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    URL: http://dx.doi.org/10.1007/BF02467186
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    Separation of the enantiomers of amino acid esters as benzophenone imine derivatives on polysaccharide-derived chiral stationary phases (1999)
    Springer
    Chromatographia 49 (1999), S. 61-64 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral stationary phases ; Benzophenone imine derivatives ; Amino acid esters ; Enantiomer separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The liquid-chromatographic separation of the enantiomers of amino acid esters as benzophenone Schiff-base derivatives on polysaccharide-derived chiral stationary phases (CSPs) is described. The performance of Chiralcel OF was superior to that of the other CSPs for resolution of benzophenone imine derivatives of amino acid ethyl and methyl esters. The enantiomers of most of the amino acid esters examined as their benzophenone imine derivatives were resolved to baseline on Chiralcel OF. The L-(−) enantiomers of all the analytes were preferentially retained on Chiralcel OF. The resolution of several imine derivatives of amino acid esters was investigated, as was the effect of eluent composition on the resolution of amino acid ethyl esters as their benzophenone imine derivatives.
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    Development and validation of an HPLC method for the simultaneous determination of clozapine and desmethylclozapine in plasma of schizophrenic patients (1999)
    Springer
    Chromatographia 49 (1999), S. 75-80 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amperometric detection ; Clozapine ; Desmethylclozapine ; Drug monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high-performance liquid chromatographic method with amperometric detection has been developed for the determination of levels of clozapine (CLZ) and its active metabolite N-desmethylclozapine (DMC) in human plasma. The analysis was performed on a 5 μm C8 reversed phase column (150×4.6 mm i.d.), with acetonitrile-phosphate buffer (pH 3.5), as the mobile phase. The detection voltage was +800 mV and the cell and column temperature were 50°C. Linear responses were obtained between 2 ng mL−1 and 100 ng mL−1. Absolute recovery for both clozapine and desmethylclozapine exceeded 88% and the detection limit was 1 ng mL−1. Repeatability, intermediate precision and accuracy were satisfactory. The method, which is rapid, sensitive and selective, has been applied to therapeutic drug monitoring in schizophrenic patients following administration of Leponex® tablets. In 21 patients in steady state at a mean daily clozapine dosage of 358 mg (ranging from 150 to 500 mg day−1), clozapine levels averaged 379 ng mL−1 (ranging from 102 to 818 ng mL−1) and DMC levels averaged 233 ng mL−1 (ranging from 70 to 540 ng mL−1). The method requires only a very small amount of plasma (100 μL), and thus it is suitable for pharmacokinetic studies, as well as for therapeutic drug monitoring.
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    URL: http://dx.doi.org/10.1007/BF02467191
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    Study of the chromatographic behavior and inclusion constants of new fluorescence agents by use of cyclodextrin additives under conditions of steady- and dynamic-state equilibrium and with fluorescence detection (1999)
    Springer
    Chromatographia 49 (1999), S. 95-104 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cyclodextrin additives ; Fluorescence agents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary We report four new derivatization agents, acridone-N-acetic acid (ARC), carbazole-9-ylacetic acid (CRA), carbazole-9-ylpropionic acid (CRP), and 2-methyl-2-carbazole-9-ylacetic acid (MCRA), with strong fluorescence emission which has low dependence on solvent polarity. The emission maxima for ARC, CRA, CRP, and MCRA were 430 nm (λex 404 nm), 368 nm (λex 335 nm), 356 nm (λex 340 nm) and 360 nm (λex 330 nm), respectively. The effects of mobile-phase composition, pH, and temperature on the liquid chromatographic retention behavior of the four fluorescence agents were investigated. An experimental model was established for calculating the inclusion constants of cyclodextrin (CD) complexes in the dynamic state, using β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) as examples, and different mobilephase compositions. On the basis of the model, the inclusion constants of the solutes in pure water (K fw) were determined by extrapolation. The thermodynamic parameters (ΔH o and ΔS o) and dissociation constantsK am for the solutes in this chromatographic system were obtained by means of capacity factor (k) values using a corresponding model formulation.
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    Effect of triethylamine in the mobile phase on the retention properties of conventional polymeric and horizontally polymerized octadecylsilica in RPLC (1999)
    Springer
    Chromatographia 49 (1999), S. 635-642 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Interaction of mobile and stationary phases ; Linear solvation energy relationships ; Triethylamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of triethylamine (TEA) in the mobile phase on the RPLC retention behavior of small organic solutes has been studied on a conventional polymeric octadecylsilica (ODS) and on a horizontally polymerized ODS. Retention factors for a set of solutes were measured on the two phases with methanol-water mobile phases containing triethylamine at different concentrations and analyzed by use of linear solvation energy relationships (LSER). Variation of the resulting LSER coefficients—v (hydrophobicity),r (polarizability),s (dipolarity),b (hydrogen-bond (HB) donating acidity), anda (HB accepting strength)—were examined to see how TEA affects the intermolecular interaction properties of the mobile and stationary phases and hence the retention of the solutes. Addition of TEA to the mobile phase changes the interaction properties of both conventionally polymerized and horizontally polymerized ODS; the effect is greater for the conventional phase. The HB donating acidity (b) of conventional polymeric ODS is significantly reduced by addition of TEA. For the mobile phases studied the magnitudes of theb andv coefficients for the horizontally polymerized ODS phase are greater than for the conventional phase. The different interaction properties of the two polymeric phases arise mainly as a result of differential adsorption of TEA, because of the very different amounts of surface silanol groups present on the two phases.
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    Preparation and evaluation ofp-tert-butyl-calix[4]arene-bonded silica stationary phases for high performance liquid chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 643-648 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; p-tert-Butyl-calix[4]arene-bonded silica ; Nuclear magnetic resonance spectrometry ; PAHs ; Nucleosides bases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method is proposed for preparation of ap-tert-butyl-calix[4]arene-bonded silica stationary phase. The chemically modifiedp-tert-butyl-calix[4]arene is attached to silica gel via the silane coupling reagent γ-(ethylenediamino)-propyl-triethoxyl-silane. The bonded phase has been characterized by29Si and13C cross polarization/magic angle spinning solid-state nuclear magnetic spectrometry. The retention behavior of polycyclic aromatic hydrocarbons (PAHs), nucleosides and bases has been investigated on the bonded phase in the reversed-phase mode.
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    Hydrolysis of microcystins and nodularin by microwave radiation (1999)
    Springer
    Chromatographia 49 (1999), S. 671-677 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microwave hydrolysis ; Microcystin ; Nodularin ; D- and L-selective amino acid determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Microwave radiation has been successfully used for hydrolysis of the hepatotoxic cyclic peptides microcystins and nodularin. Set-up of the microwave device and the operating conditions for microwave hydrolysis were optimized. Results of the microwave hydrolysis were compared with results from conventional hydrolysis for 24 h at 110°C. Microwave hydrolysis of microcystins and nodularin for as little as 10 min at 160°C results in complete cleavage of peptide bonds and high recoveries of amino acids. Enantioselective determination of amino acids was achieved by use of a previously described HPLC method after pre-column derivatization withortho-phthaldialdehyde and the chiral thiolN-iso-butyryl-cysteine.
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    Peculiarities of the mechanism of retention of imidazole derivatives when using hydroxypropyl-β-cyclodextrin as mobile phase additive (1999)
    Springer
    Chromatographia 49 (1999), S. 691-698 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Hydroxypropyl-β-cyclodextrin ; Imidazole derivatives ; Retention mechanisms ; Enthalpy-entropy compensation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two different methods have been used to investigate the retention mechanism of a series of imidazole derivatives in reversed-phase liquid chromatography (RPLC) over a range of column temperatures and with different concentrations of hydroxypropyl-β-cyclodextrin (HP-β-CD) in the mobile phase. The first approach was the separate study of each factor affecting the retention mechanism; the second method was the simultaneous variation of all these factors. Changes in Van't Hoff plots as a function of HP-β-CD concentration were examined. Enthalpy and entropy were determined for two physicochemical processes: (i) solute transfer from the mobile phase to the stationary phase, and (ii) solute complexation by HP-β-CD. These thermodynamic data showed that the mechanism of retention of the solute was dependent on the concentration of HP-β-CD in the mobile phase. For a HP-β-CD concentration,C, greater than to 4 mM, from 28°C to a critical temperature,T *, solute retention was entropy-dominated because of inclusion of the solute in the HP-β-CD cavity. AboveT * retention was enthalpy-dominated, because of interaction of the solute with the RP18 stationary phase. At firstT * increased asC was increased up to a critical value,C **; it the remained relatively constant because of auto-association of the HP-β-CD molecules in the mobile phase. Enthalpy-entropy compensation revealed that HP-β-CD-solute complexation had a greater effect on retention than RP18 stationary phase-solute interaction. This confirms that the main parameter determining retention in RPLC is the distribution of the solute in the mobile phase, and that interactions with the stationary phase play a minor role.
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    Characterisation of paint layers in Chinese archaelogical relics by pyrolysis-GC-MS (1999)
    Springer
    Chromatographia 49 (1999), S. 268-272 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Mass spectrometry ; Analytical pyrolysis ; Chinese art objects ; Mercury analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A few samples of polychrome Chinese archaeological objects of art have undergone analytical pyrolysis coupled with GC-MS to evaluated the possibility of contemporary characterization of the pigments as well as the organic media used. The red pigment cinnabar (HgS) is easily media used. The red pigment cinnabar (HgS) is easily detected, whereas in the case of organic components positive results are only found where the matrices are resistant to archaeological environmental conditions.
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    Analysis of commercial ceramides by non-aqueous reversed-phase liquid chromatography with evaporative light-scattering detection (1999)
    Springer
    Chromatographia 49 (1999), S. 241-248 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Non-aqueous reversed-phase liquid chromatography ; Evaporative light-scattering detection ; Octadecyl grafted silica ; Ceramides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper describes the development of a chromatographic system for analysis of commercial ceramides structurally similar to those found in the stratum corneum. The ceramides used in this study contain different amine based (phytosphingosine, sphingosine and dihydrosphingosine) and fatty acids of different chain lengths and with different functional groups (hydroxylated and unsaturated). Non-aqueous reversed-phase (NARP) liquid chromatography with evaporative light-scattering detection (ELSD) were the techniques chosen in accordance with the nature of the ceramides. The eluent strength and the potential selectivity of different organic solvents were investigated. On a C18-bonded silica, the most promising chromatographic conditions employed a gradient from ACN-THF, 95∶5, to ACN-THF-PrOH, 35∶5∶60, in 15 min with a constant concentration of TEA (10 mM) and a stoichiometric amount of formic acid.
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    High-performance liquid chromatographic method for separation and quantification of intact glucosinolates (1999)
    Springer
    Chromatographia 49 (1999), S. 281-284 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Glucosinolates ; Rapseed-mustard ; Brassica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple, economical and efficient HPLC method has been developed for the separation and determination of the individual glucosinolates in rapessed and mustard. The method involves single-step extraction of glucosinolates with boiling water and separation of the individual glucosinolates on a Novapack RP-18 column (3.9 mm ×150mm) with 0.2 M ammonium sulphate as mobile phase. Peaks were monitored at 229 nm. All major glucosinolates could be eluted within 10 min. The method proved effective for routine analysis of glucosinolates.
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    Polybutadiene-coated zirconia packing materials in solvating gas chromatography using carbon dioxide as mobile phase (1999)
    Springer
    Chromatographia 49 (1999), S. 431-435 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Supercritical fluid chromatography ; Solvating gas chromatography ; Polybutadiene coated zirconia ; CO2 mobile phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In this paper, practical considerations of column efficiency, separation speed, thermal stability, and column polarity of capillary columns packed with polybutadiene-coated zirconia were investigated under solvating gas chromatography (SGC) conditions using carbon dioxide as mobile phase. When compared with results obtained from conventional porous octadecyl obtained from conventional porous octadecyl bonded silica (ODS) particles, PBD-zirconia particles produced greater change in mobile phase linear velocity with pressure than conventional ODS particles under the same conditions. The maximum plate number per second (Nt) obtained with a 30 cm PBD-zirconia column was approximately 1.5 times higher than that obtained with an ODS column at 100 °C. Therefore, the PBD-zirconia phase is more suitable for fast separations than conventional ODS particles in SGC. Maximum plate numbers per meter of 76,900 and 63,300 were obtained using a 57 cm×250 μm i.d. fused silica capillary column packed with 3 μm PBD-zirconia at 50 °C and 100 °C, respectively. The PBD-zirconia phase was stable at temperatures up to 320 °C under SGC conditions using carbon dioxide as mobile phase. Polarizable aromatic compounds and low molecular weight ketones and aldehydes were eluted with symmetrical peaks from a 10 cm column packed with 3 μm PBD-zirconia. Zirconia phases with greater inertness are required for the analysis of more polar compounds by SGC.
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    Estimation of retention times of homologous series in temperature programmed gas chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 509-512 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Homologous series ; Retention times
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary It is shown how to estimate the retention times of homologous series members in linear temperature programmed gas chromatography with the aid of a spread-sheet. Both the ease of estimation and the accuracy of the estimation depend on whether the homologue is eluted during the rising portion of the temperature program or the hold time at the end, and also on whether the homologous series is eluted from one injection or a number of injections. When all members of the series elute in the one chromatographic run the percentage standard deviation of the predicted retention times from the experimental retention times is 0.1. When members of the series elute in different chromatographic runs, the percentage standard deviation of predicted times from experimental times is 0.6, compared with an experimental percentage standard deviation for replicates of 0.5.
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    Determination of flupoxam residues in soil by high performance liquid chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 535-538 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solid phase extraction ; Herbicides in soil ; Flupoxam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance liquid chromatography with UV detection was used to determine the residues of flupoxam (a new herbicide) in soils. Soil samples were extracted with aqueous methanol. The soil extracts were cleaned up and concentrated using two solid phase extraction columns: a polymeric stationary phase based on a polystyrene-divinylbenzene resin (Lichrolut EN) and alumina. Recovery experiments were performed at ppb levels in spiked soil samples. The recovery was 76±1.7% for flupoxam in the range 5–100 μg kg−1 of soil. Limit of determination was 3 μg kg−1.
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    Stereochemical resolution of racemates, in HPLC, using a chiral stationary phase based upon immobilized α-chymotrypsin. II. Enzyme chiral separations (1999)
    Springer
    Chromatographia 49 (1999), S. 606-614 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; α-Chymotrypsin-CSP ; Enzymatic chiral separations ; Loadability evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Several racemates has been resolved according to an enzymatic recognition mechanism on an α-chymotrypsin chiral stationary phase. The loadability of the ACHT-CSP has been evaluated both in buffered and non-buffered mobile phases under the enzymatic process and compared with the loading capacity obtained by the structural recognition process.
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    HPLC resolution of the enantiomers of glycidyl sulfides and glycidyl selenides on amylose tris-(phenylcarbamate) stationary phase (1999)
    Springer
    Chromatographia 49 (1999), S. 572-574 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Enantioseparations ; Amylose phenylcarbamate phase ; Glycidyl sulfides ; Glycidyl selenides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The resolution of the enantiomers of a series of glycidyl sulfides and glycidyl selenides has been examined on a chiral stationary phase prepared by coating aminopropylated silica gel with amylose tris-(phenylcarbamate). Most of the enantiomers of glycidyl monosulfides and monoselenides could be resolved satisfactorily but those of the disulfides could not. The effects of solute structure and of the concentration of 2-propanol in the mobile phase on retention and resolution were investigated.
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    Determination of cisplatin, transplatin and amminetri-chloroplatinate by high performance liquid chromatography in one run using 4-methyl-2-thiouracil as derivatizing agent (1999)
    Springer
    Chromatographia 49 (1999), S. 562-566 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cis-diamminedichloroplatinum (II) ; Transdiamminedichloroplatinum (II) ; Amminetri-chloroplatinate ; 4-Methyl-2-thiouracil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary We have developed a simple, rapid, selective and sensitive method for detecting the antitumour agent cis-diamminedichloroplatinum (II) (cisplatin) (CDDP) and its toxic impurities trans-diamminedichloroplatinum (II) (transplatin) (TDDP) amminetri-chloroplatinat (ATCP) anion using HPLC in one run. By using 4-methyl-2-thiouracil (MTU) as a derivatizing agent, new compounds have been formed from the Pt compounds and separated on a μ-Bondapak C18 column with isocratic elution and detection at 315 nm. Reactant concentration, methanol content, pH and the reaction time on yield of derivatives were investigated and the optimum conditions for the detection response were defined. The derivatives of each of the three platinum compounds formed in an acetate buffer solution containing 40% (v/v) methanol and 0.9% KCl solution at pH 3.7 and ambient temperature were only stable for one hour.
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    URL: http://dx.doi.org/10.1007/BF02467760
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    Efficiency of direct solid-phase microextraction from water-comparison of different fibre types including a new C8-coating (1999)
    Springer
    Chromatographia 49 (1999), S. 686-690 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid-phase microextraction ; Fibre coating ; Volatile organic compounds ; Semi-volatile organic compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The efficiency of direct solid-phase microextraction (SPME) was determined for 27 selected volatile and semivolatile organic compounds (BTEX, chloro- and bromobenzenes, chlorinated pesticides and PCBs). The fibres used were 7μm polydimethylsiloxane (PDMS), 30μm PDMS, 100μm PDMS, 65μm PDMS-divinylbenzene, 85μm polyacrylate, 65μm Carbowax-divinylbenzene, 75μm Carboxen-PDMS and a new 65μm C8 fibre. Extraction yields for these compounds were calculated under standardised conditions: 75μm Carboxen-PDMS was found to be the most efficient fibre for compounds with low boiling points. Although 65μm C8 can be used for extraction of all compounds studied, in no one case is it the most effective coating. 100μm PDMS and the more polar coatings can be used for a broad range of compounds, whereas application of 7μm and 30μm PDMS cannot be recommended. Inter-fibre comparison revealed significant differences between three different Carboxen-PDMS fibres. The results enable suitable coatings to be chosen for each of the 27 compounds and for substances with similar properties.
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    URL: http://dx.doi.org/10.1007/BF02466913
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    The GC determination of cisplatin as platinum(II) from pharmaceutical preparations and blood sample of cancer patients (1999)
    Springer
    Chromatographia 49 (1999), S. 249-252 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Cisplatin determination ; Blood analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A capillary gas chromatographic method is described for the determination of cisplatin based on the complexation of platinum(II) with bis(isovalerylacetone) ethylenediimine (H2IVA2en) and extraction in chloroform. The chromatography was carried out on a BP1 or a BP5 column with an FID. Copper(II), nickel (II) and palladium(II) separated completely and did not affect the determination of platinum(II). The method was applied of the determination of cisplatin in a pharmaceutical preparation and blood samples of cancer patients after infusion of cisplatin. The amounts of cisplatin in blood were found to be within 246–283 ng mL−1 with a C.V. of 2.35–4.26%.
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    URL: http://dx.doi.org/10.1007/BF02467551
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    Transition metal complex stationary phases for the CGC analysis of ethers, thioethers and ketones (1999)
    Springer
    Chromatographia 49 (1999), S. 273-280 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Complexation stationary phases ; Bonding metal complexes ; Capillary columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of polysiloxanes with cyano or thiol groups as stationary phases for complexation gas chromatography is discussed. The polymers were obtained via polycondensation followed by polymerisation of the corresponding dichloro- or dimethoxy-silanes. Both the phases were modified by bonding transition metal chlorides with were modified by bonding transition metal chlorides with cyano (CuCl2 or CoCl2) and thiol groups (NiCl2 or CoCl2). The phases were examined in order to determine their application to the analysis of ethers, thioethers and ketones. Due to the presence of lone electron pairs on oxygen or sulphur atoms, the compounds should be capable of specific interacting with the electron-withdrawing centre of the liquid stationary phases. A number of retention parameters (retention indices, molecular retention indices and specific retention volume) were determined, which allowed characterisation of specific interactions between the bonded metal and the compound analysed. The results also enabled assessment of the influence of the structure of the compounds on their retention. The measurements were also carried out for the phases with free SH and CN groups as reference phases. The work demonstrates that the phases obtained may be useful for effective separations.
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    URL: http://dx.doi.org/10.1007/BF02467556
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    Unexpected behavior of digoxin at elevated temperatures in reversed-phase liquid chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 306-308 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Digoxin and digoxigenin ; Temperature effects ; Pore size effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Increased retention of digoxin has been observed at elevated temperatures on both 10 nm and 30 nm porediamter, RP-18 packing. This result is the opposite effect compared with the decreased retention under the same conditions with digoxin aglycon-digoxigenin. Rotation around the C−C σ-bonds in the digoxin molecule is presumed; the rod-like molecules of the newlyobtained digoxin penetrate stationary phase pores more easily thus increasing retention.
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    URL: http://dx.doi.org/10.1007/BF02467561
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  • 47
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    Potentiometric detection of monovalent anions separated by ion chromatography using all solid-state contact PVC matrix membrane electrode (1999)
    Springer
    Chromatographia 49 (1999), S. 338-342 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion chromatography ; Monovalent anions determination ; Potentiometric detection ; Ion selective PVC-matrix electrode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An all solid-state contact tubular PVC-matrix membrane electrode has been applied for potentiometric detection of inorganic and organic monovalent anions using phosphate and hydrogen phosphate eluents at low concentrations. This is a “monovalent detection method” as the selectivity of the electrode towards monovalent anions results in some other anions being undetected unless the concentration of those other anions is higher than 10−3 mol dm−3 in the sample solution injected. It takes only eight minutes to complete the separation with a good resolution. Theoretical and practical considerations are discussed, and in particular, sensitivity, linearity, detection limit and dynamic behaviour are presented. The use of an all solid-state contact bromide-selective electrode as a detector offers so far the best simultaneous sensitivity toward all anions when compared with other detection methods. Determination of Cl− and NO3 − ions in river, rain and drinking water samples without any further sample preconcentration has been successfully achieved. The detection limit is sub-ppb for most of anions in a 20 μL injection volume.
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    URL: http://dx.doi.org/10.1007/BF02467567
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    Normal-phase high performance liquid chromatographic separation and characterization of short- and long-chain triacylglycerols (1999)
    Springer
    Chromatographia 49 (1999), S. 363-368 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Evaporative light scatering detection ; APCI mass spectrometry ; Triacylglycerols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Short- and long-chain triacylglycerols (SLCT) are a family of lipids prepared by chemical or enzymatic interesterification of triacetin, tripropionin and/or tributyrin, and long-chain (C16!18) hydrogenated vegetable oils. In this study, a normal-phase cyanopropyl high-performance liquid chromatographic (HPLC) method was developed for the separation and quantification of SLCT. The method is capable of separating SLCT mixtures, free fatty acids and the neutral lipid classes of saturated long-chain triacylglycerols, diacylglycerols and monoacylglycerols. To characterize the specific SLCT classes, a normal-phase HPLC procedure using a non-modified silica column was developed to separate the SLCT into individual isomers based on total carbon number and position of fatty acids on the glycerol backbone. Online coupling with a mass detector (LC/MS) allowed the identification of the individual triacylglycerol structures.
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    URL: http://dx.doi.org/10.1007/BF02467607
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  • 49
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    Comparison of octadecyl bonded titania phases (1999)
    Springer
    Chromatographia 49 (1999), S. 424-430 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Octadecyl titania ; Surface hydrosilation ; Solid-state NMR C7
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The structure of a C18 phase based on titania (C18-A), synthesized by the method of solution polymerization, is investigated by diffuse reflectance infrared Fourier transform (DRIFT) and solid-state nuclear magnetic resonance (NMR) spectroscopy. The findings are compared with the results of a second C18 phase based on titania (C18-B) which was synthesized by the method of surface hydrosilation. The dynamic behavior of both phases is examined by1H MAS NMR detection of spinlattice relaxation times in the rotating frame (T1pH) and conventional spin-lattice relaxation times (T1). Due to a smaller ligand density, phase C18-A appears to be a somewhat more mobile than phase C18-B. The chromatographic capability of the phase C18-A is demonstrated by the separation of samples containing benzene derivates or anilines. The elution order is analogous to the phase C18-B, but for both test mixtures the polarity of the mobile phase has to be increased. Phase C18-A is classified as being polymeric by the Sander and Wise test, whereas phase C18-B shows intermediate retention behavior.
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    URL: http://dx.doi.org/10.1007/BF02467618
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    Averaging the pressure and flow rate of the carrier gas in a gas chromatographic column (1999)
    Springer
    Chromatographia 49 (1999), S. 449-453 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Average column pressure ; Average column flow ; Specific retention volume ; Distribution coefficient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A systematic derivation of corresponding equations shows that averaging the pressure and the flow rate of the mobile phase in a gas chromatographic column over the column length and over the time that an unretained component resides in the column, requires the use of three different compressibility correction factors,j 2 1 ,j 3 2 , andj 4 3 . When multiplied by the adjusted retention volume,V R-VM, the Martin and James mobile phase compressibility correction factorj 3 2 , only, produces the value of specific retention volume,V g T , which is connected unambiguously with the thermodynamic phase distribution coefficient,K, of the sorbate.
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    URL: http://dx.doi.org/10.1007/BF02467622
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    Solid phase microextraction of volatiles from water using open cap vials (1999)
    Springer
    Chromatographia 49 (1999), S. 513-519 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid phase microextraction ; Open cap vials ; Volatile compounds (BTEX) ; Water matrix
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The testing of open cap vials in headspace solid-phase microextraction combined with capillary gas chromatography is reported. The losses of volatile analytes from such vials were analyzed theoretically and investigated experimentally. The benzene, toluene, ethylbenzene, and xylene isomers spiked in water were used as model compounds. Extraction yields and precision obtained under optimized experimental conditions as exposure time, desorption time and temperature were compared applying vials with open caps or sealed with teflon lined septa.
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    URL: http://dx.doi.org/10.1007/BF02467751
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    Synergistic effect of mixed stationary phase in gas chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 567-571 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Mixed stationary phase ; Calixarenes ; Crown ethers ; Cyclodextrins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Mixed stationary phases containing of 25,27-dibutoxy-5,11,17,23-tetra-tert-butyl-26,28-diundecenyloxy calix [4]arene (C[4]B)+ω-undecylomethyl-18-crown-6 polysiloxane (PSO-11-18-C-6) and C[4]B polysiloxane (PSO-C[4]B)+permethyl-β-cyclodextrin (PM-β-CD) were investigated in capillary gas chromatography. By comparing their selectivity for positional isomers with that of the corresponding individual pure stationary phases, synergistic effects were found.
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    URL: http://dx.doi.org/10.1007/BF02467761
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    Gas chromatographic determination of 2-chloro-1-[[4-[(2,6-dichlorophenoxy)methyl]phenyl]methoxy]-4-methoxybenzene (SCH 48973), a potent anti-picornaviral agent, in dog serum (1999)
    Springer
    Chromatographia 49 (1999), S. 575-578 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Electron capture detector ; Anti-picornaviral agent in dog serum ; Enteroviruses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A gas chromatographic assay for the determination of SCH 48973, a potent broad spectrum anti-picornaviral agent, was developed and validated in dog serum. The method involved extraction with organic solvent followed by separation on a capillary column (DB-1) with quantitation by an electron-capture detector. The method was sensitive with a limit of quantitation of 10 ng mL−1. The linearity of the method was satisfactory as indicated by correlation coefficients of 〉0.999 and visual examination of the calibration curves. The method was precise with a coefficient of variation ranging from 2.3 to 13.2% and accurate with a bias ranging from −9.1 to 7.9%. Moreover, SCH 48973 was stable in dog serum after being subjected to three freeze-thaw cycles. The assay was shown to be sensitive, specific, accurate and precise, and reliable for use in pharmacokinetic or toxicokinetic studies.
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    URL: http://dx.doi.org/10.1007/BF02467763
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    High performance liquid chromatography coupled to nuclear magnetic resonance spectroscopy and mass spectrometry applied to plant products: Identification of ecdysteroids fromSilene otites (1999)
    Springer
    Chromatographia 49 (1999), S. 374-378 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; NMR spectroscopy and mass spectrometry ; Plant products ; Silene otites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary HPLC coupled in parallel to nuclear magnetic resonance (NMR) and mass spectrometry (MS) has been used to obtain1H NMR and mass spectra of a number of ecdysteroids present in an extract of the plantSilene otites. Reversed phase gradient chromatography was performed using a D20-acetonitrile-based solvent system. NMR and mass spectra were obtained for integristerone A, 20-hydroxyecdysone, 2-deoxy-20-hydroxyecdysone and 2-deoxyecdysone to provide structural confirmation using continuous and stopped flow HPLC-NMR. The combined HPLC-NMR-MS system described here provided a more comprehensive analysis of the ecdysteroids present in the extract than HPLC-NMR alone.
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    URL: http://dx.doi.org/10.1007/BF02467609
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    Analysis of organic pollutants in sewage by supercritical fluid extraction (1999)
    Springer
    Chromatographia 49 (1999), S. 399-405 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid phase adsorption ; Supercritical fluid extraction ; Sewage ; Organic pollutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Analytical methods have been developed for the determination of organic pollutants of intermediate polarity in sewage. Water samples are first passed through a solid phase adsorption cartridge. The analytes are then extracted from the absorbent with supercritical CO2 into a small volume of trapping solvent. Finally, the extracts are analyzed directly by capillary gas chromatography and gas chromatography-mass spectrometer. The various parameters (pressure, temperature, type and concentration of modifiers, trapping solvent, flow rate and volume of supercritical fluid and equilibrium time) influencing the efficiency of extraction were studied. Extraction efficiencies for the test compounds are 〉70%, and relative standard deviations are 〈4.6% (n=3). The methods established were applied to the analysis of sewage at the Lanzhou Wastewater Treatment Plant, China. 66 organic pollutants were detected, of which 15 compounds appeared in the list of priority pollutants suggested by the US EPA.
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    URL: http://dx.doi.org/10.1007/BF02467613
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    A system for predicting the retentions of O-alkyl, n-(1-methylthioethylideneamino) phosphoramidates on RP-HPLC (1999)
    Springer
    Chromatographia 49 (1999), S. 444-448 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; O-alkyl, O-(1-methylthioethylideneamino) phosphoramidates ; Quantitative structure-retention relationship (QSRR) ; Reversed-phase LC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary By using factor analysis, cluster analysis and multiple linear regression methods, two parameters, FHF and ECCR, were selected from eight solute-related structure parameters as showing the best correlation with retention data. The relationship between the retention data (k) and these two structure parameters were established for ten O-alkyl, O-(1-methylthioethylideneamino) phosphoramidate compounds under the experimental conditions studied. Retention data (k) for six other compounds that have a high correlation with structure parameters were predicted using these QSRR equations. The system was evaluated by comparing the experimentalk values with the predicted ones. Good agreement was obtained between the experimental and predictedk values.
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    URL: http://dx.doi.org/10.1007/BF02467621
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