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Year
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  • 101
    Electronic Resource
    Electronic Resource
    Determination of chloroethenes in environmental biological samples using gas chromatography coupled with solid phase micro extraction (1996)
    Springer
    Chromatographia 42 (1996), S. 313-317 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290316
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  • 102
    Electronic Resource
    Electronic Resource
    Extraction of local anaesthetics from human blood by direct immersion-solid phase micro extraction (SPME) (1996)
    Springer
    Chromatographia 43 (1996), S. 59-62 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272822
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  • 103
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292979
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  • 104
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292985
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  • 105
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292947
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  • 106
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292953
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  • 107
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02293005
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  • 108
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02270997
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  • 109
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02293004
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  • 110
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02293008
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  • 111
    Electronic Resource
    Electronic Resource
    Separation of a gasoline on an open tubular column with 1.3 million effective plates (1996)
    Springer
    Chromatographia 42 (1996), S. 63-71 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; High efficiency open tubular columns ; Columns connected in series ; Gasoline analysis ; Detailed hydrocarbon analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary More than 1.3 million effective plates were produced by a column 450 meters long, 200 μm inner diameter. The column was built up by connecting nine 50 meter columns in series. The sum of the efficiencies of the individual pieces equalled the efficiency of the combined column. Up to 970 components were differentiated in a gasoline standard.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02271057
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  • 112
    Electronic Resource
    Electronic Resource
    A computerized analysis of the sulfur content in diesel fuel by capillary gas chromatography with flame photometric detector (1996)
    Springer
    Chromatographia 42 (1996), S. 631-638 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; flame photometric detector ; Sulfur in diesel fuel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method is proposed for the computerized determination of sulfur in diesel fuel by capillary gas chromatography with a flame photometric detector (FPD). The diesel fuel is injected in the gas chromatograph after dilution with n-hexane. After recording the chromatogram, the sulfur content in the diesel fuel (mg L−1 or w/w) is given directly by an integrator provided with a Basic card or by a personal computer in which the algorithm of the calibration curve has been entered. Use of a calibration curve does not require the identification of the numerous sulfur compounds present in diesel fuel. The calibration curve was corrected for the quenching effect that the hydrocarbon components of the diesel fuel produce on the detector response. The method was tested using diesel fuel with a known sulfur concentration and was found to be very accurate; it is reproducible, fast and may be automated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267694
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  • 113
    Electronic Resource
    Electronic Resource
    Classification of the botanical origin of cinnamon by solid-phase microextraction and gas chromatography (1996)
    Springer
    Chromatographia 42 (1996), S. 639-646 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Semivolatile flavor compounds ; Cinnamon ; Solid-phase microextraction ; Chemometric classification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The conditions which affect the reproducibility of characteristic chromatographic profiles of semivolatile compounds from true cinnamon and cassia by headspace solid-phase microextraction are determined. Optimum conditions for sample amount, vial size, temperature, sampling time, and fiber type for steady state sampling conditions are identified. Vial size was an unexpected critical parameter possibly related to the build up of internal ternal pressure during sample heating followed by expulsion of a portion of the vapor phase through the septum as it was punctured by the syringe. Gas chromatography with ion trap mass spectrometry was used to identify the major volatile compounds in cassia and true cinnamon. Reasonable semi-quantitative agreement (r 2〉0.87 and generally greater than 0.93) was observed for the major semivolatile compounds isolated by headspace solid-phase microextraction and solvent-assisted supercritical fluid extraction. The extracts isolated by solid-phase microextraction contained relatively high concentrations of terpene-type compounds in low abundance in the solvent-assisted supercritical fluid extracts, but these compounds were of little value in distinguishing the botanical origin of authentic cinnamon and cassia samples. The latter were easily distinguished by the presence of eugenol and benzyl benzoate in true cinnamon, that was absent in cassia, and the presence of coumarin and δ-cadinene, in cassia, that was either absent or in low concentration in true cinnamon. Headspace solid-phase microextraction provides a rapid and simple method for establishing the botanical origin of the principal cinnamons of commerce.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267695
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  • 114
    Electronic Resource
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    CGC/AED and CGC/ECD/NPD comparison for the determination of acaricides in honey after hexane/acetone extraction (1996)
    Springer
    Chromatographia 42 (1996), S. 130-134 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Atomic emission, electron capture ; and nitrogen phosphorus detection ; Honey ; Acaricides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The performance of a gas chromatographic system coupled to an atomic emission detector (GC/AED) is tested by comparison with a two-dimensional gas chromatographic system equipped with capillary columns of different polarity and simultaneous electron capture and nitrogen-phosphorus detection (ECD/NPD), for the determination of the acaricides chlordimeform, bromopropylate, amitraz and coumaphos on spiked honey samples. The acaricides were extracted with ann-hexane/acetone mixture (80∶20, v/v) with a further clean-up step on an octadecylsilane cartridge. The 193 nm carbon emission line is the best choice in terms of sensitivity whereas the ECD/NPD system gives better selectivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269641
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  • 115
    Electronic Resource
    Electronic Resource
    Synthesis of chemically bonded squalene(ane) phases for microcolumn gas chromatographic separation of low-molecular-weight hydrocarbons in extraterrestrial atmospheres (1996)
    Springer
    Chromatographia 42 (1996), S. 141-146 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Low-molecular-weight hydrocarbons ; Extraterrestrial atmospheres ; Chemically bonded squalene(ane) phase ; 13C and29Si CP-MAS NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Chemically bonded squalene(ene) phases have been synthesized via a hydride modified silanization process using dimethylchlorosilane, triethoxysilane and trichlorosilane. The surface structure of the bonded phases were characterized with DRIFT and solid state NMR studies. The results of the latter indicate successful bonding of a non-terminal olefin to the silica surface and that bonding of individual squalene molecules appeared not to occur at the same site(s) presumably due to steric hindrance. Among the phases examined, the trichlorosilane-based material exhibits better chromatographic properties probably due to greater surface coverage and hence effective non-polar interaction between the solutes and the bonded ligands. Under isothermal conditions, the present packings produced fast and efficient separation of C1–C4 saturated hydrocarbons on shorter columns than similar columns containing alkyl- or bidentate alkyl-modified silica packings at low column head pressure and are thermally stable at temperatures up to 250°C or higher.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269643
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  • 116
    Electronic Resource
    Electronic Resource
    Simultaneous gas chromatographic determination of methanol and free glycerol in biodiesel (1996)
    Springer
    Chromatographia 42 (1996), S. 431-434 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Fatty acid methyl esters ; Biodiesel ; Methanol ; Glycerol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The methanol and free glycerol content of vegetable oil methyl esters used as diesel fuel (biodiesel) is very important in describing the quality of this fuel and is therefore limited by specifications. A previously described GLC method for the determination of free glycerol in biodiesel has been further developed and also allows the simultaneous determination of methanol. Sample preparation includes dissolving in dimethylformamide, silylation with bis-trimethylsilyltrifluoracetamide (BSTFA) and separation on a methylsilicone fluid, coated-capillary column using either FID or MS-detection. Ethanol and 1,4-butanediol were used as internal standards. Both detection systems show sufficient sensitivity for concentrations relevant to biodiesel samples. The recovery was tested using a RME-sample containing known amounts of methanol and glycerol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272135
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  • 117
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    Gas chromatographic and differential scanning calorimetric studies of new bonded silicas in connection with transition phenomena (1996)
    Springer
    Chromatographia 42 (1996), S. 451-461 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Bonded silicas ; Phase transitions ; Differential scanning calorimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In order to give a molecular interpretation to the phase transition observed with densely bonded octadecyl-silicas in reversed phase liquid chromatography (RPLC) as well as in gas chromatography (GC), nine new bonded silicas were prepared including grafts with polar groups at the extremities of long spacers (18 carbon atoms). The interpretation is simplified by using large-pore macroporous substrates and inverse GC in conjunction with differential scanning calorimetry (DSC) as the test method. A phase transition is observed in almost all cases, but the temperature range is lower and more extended in comparison to the dimethyloctadecyl reference silica. An interpretation of the phase transition is given, based on the folding of the chains and the resulting “autodensification” of the layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272138
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  • 118
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    Electronic Resource
    Capillary gas chromatography of double-base propellants (1996)
    Springer
    Chromatographia 42 (1996), S. 593-594 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Double-base propellants ; Nitroglycerin ; Centralite I ; Dibutyl phthalate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation and quantitative determination of propellant constituents on short, wide-bore fused-silica capillary columns, coated with crosslinked methylsilicone phase was investigated. The analytical results were quite satisfactory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290298
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  • 119
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    Determination of partition coefficients and residual solvent for polymer drying applications (1996)
    Springer
    Chromatographia 43 (1996), S. 31-38 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Partition coefficients ; Henry's constants ; High density polyethylene ; Polymer drying
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gas-solid partition coefficients (K) for n-hexane in high density polyethylene (HDPE) have been measured at conditions applicable to large-scale drying utilizing a novel headspace method. The method features considerable versability and simplicity due to the control of experimental conditions designed to favor full extraction of the analyte into the headspace. By combining this full extraction technique with a traditional static headspace experimental scheme, a method which measuresK and residual concentration is achieved. The results show that partition coefficients differ significantly between HDPE in its virgin powder and pellet forms, as well as among various HDPE grades. The differences are shown to be attributable to differences in % crystallinity of the specific polymer. Data collected over a wide range of hexane concentrations reveals saturation levels (solubilities) which correspond to crossover from evaporative to diffusion-controlled drying.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272818
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  • 120
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    Determination of formaldehyde in foods, biological media and technological materials by headspace gas chromatography (1996)
    Springer
    Chromatographia 43 (1996), S. 625-627 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace sampling ; Formaldehyde ; Plastics ; Foods ; Biological samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A modified headspace gas chromatographic method, based on polycondensation with formaldehyde, has been developed for derivatization with formaldehyde in foods, biological media and other products. The method provides the possibility of obtaining results within three minutes, which is of significant importance for the control of food and cosmetics production and the quality of polymer products based on formaldehyde, as well as for biological monitoring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292978
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  • 121
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    The physical meaning of the corrected retention volume (1996)
    Springer
    Chromatographia 43 (1996), S. 159-162 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Gas pressures ; Gas compressibility ; Retention volumes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The true meanings of the so-called corrected retention volume and the specific retention volume are explained in the light of the recent paper by Davankov.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292945
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  • 122
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    Use of incremental models to estimate the retention indexes of aromatic compounds (1996)
    Springer
    Chromatographia 43 (1996), S. 163-176 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention index estimation ; Aromatic compounds ; Incremental models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Pure topologically based incremental models have been developed in order to estimate the retention indexes of aromatic compounds substituted with groups containing the hetero atoms nitrogen, oxygen and halogens. The bond-types of the compounds are counted and used as molecular descriptors. The observed estimation errors are about 1 % for compounds containing no hetero atoms and for those containing halogenated substituents; the errors are approximately 2 % for aromatic compounds with nitrogen- and oxygen-containing substituents. The method is validated by prediction of the retention indexes for an additional group of aromatic compounds (the validation data set).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292946
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  • 123
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    Investigation of gas chromatographic interaction mechanism on permethylated cyclodextrins by molecular modelling (1996)
    Springer
    Chromatographia 43 (1996), S. 187-194 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Molecular modelling ; Molecular mechanics calculations ; Permethylated α-, β- and γ-cyclodextrins ; Interaction mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The capillary gas chromatographic retention behavior of α-pinene and tricyclene has been investigated on stationary phases of different polarities. On all but one of the columns employed, tricyclene eluted before α-pinene; only permethylated β-cyclodextrins dissolved in moderately polar polisiloxanes gave a reversed elution order. The intermolecular interactions which caused the unexpected retention behavior were investigated in detail, applying methods of computer simulation. To achieve this, we have developed a calculation algorithm on the basis of molecular mechanical optimizations and programmed it in a macro. This makes it possible to systematically investigate a given configuration space in which all the possible interactions can take place. It was shown that permethylated β-cyclodextrin as host molecule for both guest molecules offers an optimum cavity size. As a result the number of energetically favorable contacts between host and guest molecules as well as the strength of the interactions in this stationary phase were larger. As a consequence the elution order, normally only influenced by the vapor pressure of the compounds at a given temperature, was changed. Nonspecific interactions played an especially important role for these kinds of substances.
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    URL: http://dx.doi.org/10.1007/BF02292949
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    Evaluation of 3,5-stigmastadiene content of edible oils: Comparison between the traditional capillary gas chromatographic method and the on-line high performance liquid chromatography-capillary gas chromatographic analysis (1996)
    Springer
    Chromatographia 43 (1996), S. 195-199 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography-gas chromatography ; Gas chromatography ; 3,5-Stigmastadiene ; Cold pressed olive oil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The quantitation of 3,5-stigmastadiene and other steroidal hydrocarbons, commonly known as steradienes, is a valid tool for the recognition of refining (in particular bleaching) of edible oils; the evidence of this process is nowadays of a great interest due to growing market for “virgin”, cold-pressed, “natural” oils. Due to the long time required (about 4 hours) and the amount of solvents employed (about 650 mL) to perform the official analysis, other methods have been recently proposed, the most important of which involves high performance liquid chromatography coupled with capillary gas chromatography (HPLC-GC). In this study the results of ten oil samples, analysed by both the official method and HPLC-GC, are reported and the two methods compared and discussed, for routine use, in terms of sample preparation, time of analysis and setting up, difficulty and reproducibility.
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    URL: http://dx.doi.org/10.1007/BF02292950
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    A study on the preparation and characteristics of zeolite membrane PLOT column by in-situ synthesis (1996)
    Springer
    Chromatographia 43 (1996), S. 211-214 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Zeolite membrane PLOT columns ; In-situ synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation of a zeolite membrane PLOT column by in-situ synthesis is described. The advantages of this new column are discussed. Some analytical applications to alkanes, arenes, esters, alkyl halides and ethers on the zeolite membrane PLOT column compared with those on a coated zeolite PLOT column are reported.
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    URL: http://dx.doi.org/10.1007/BF02292954
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    Determination of acidic chlorinated pesticides in water: Comparison of official EPA method 515.1 and liquid-solid extraction HPLC/UV and HPLC/PBMS analyses (1996)
    Springer
    Chromatographia 43 (1996), S. 279-284 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Column liquid chromatography ; ECD, UV and MS detection ; EPA Method 515.1 ; Chlorinated acidic pesticides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A comparison of the official EPA method 515.1 for determination of chlorinated acidic pesticides and a modification of it is illustrated. Extraction of the analytes from water and their determination and quantitation is by gas chromatography-electron capture detection (GC-ECD), liquid chromatography-UV detection and liquid chromatography-particle beam mass spectrometry. Although HPLC-PBMS was found to be less sensitive than the GC-ECD method, it was, nevertheless, more sensitive than HPLC-UV. The modified method is simpler, quicker and allows more accurate determination of pesticides in aqueous samples.
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    URL: http://dx.doi.org/10.1007/BF02270995
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    Fast determination of nicotine and 3-ethenylpyridine in indoor environments (1996)
    Springer
    Chromatographia 43 (1996), S. 296-300 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Thermal desorption ; Ion-pair column liquid chromatography ; Nicotine, 3-ethenylpyridine ; Environmental tobacco smoke
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Different sampling and analysis techniques for the determination of gas-phase nicotine and 3-ethenylpyridine in environmental tobacco smoke are reported. Graphitized carbon traps, annular diffusion denuders, and nebulizer collectors have been used as sampling devices in combination with either thermal desorption or with water extraction. Capillary gas chromatography and ion-pair reversed-phase chromatography were applied to desorbed and liquid samples obtained in an intercomparison indoor study. The methods developed here show some advantages over existing methods in terms of analysis time, sensitivity and loading capacity.
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    URL: http://dx.doi.org/10.1007/BF02270998
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    Operating the pulsed discharged detector in both the electron-capture and photoionization modes within the same GC analysis (1996)
    Springer
    Chromatographia 43 (1996), S. 353-360 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Electron-capture detector ; Photoionization detector ; Pulsed discharge detector
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Since the electron-capture detector (ECD) is highly selective, it is imperative to use a more universal ionization detector in conjunction with the ECD in order to detect non-capturing or weakly capturing compounds. Also in an EC study of weakly or moderately strong electron-capturing compounds, it is necessary to identify the EC peak of the compound by identifying the major component with an ionization detector. In this paper we have shown that the pulsed discharge detector can be interchanged between the EC and the helium ionization modes within 4–6 s. The application of this procedure has been illustrated with a mixture of alkane/alkene chlorocompounds. The interchange between EC and argon photoionization modes has also been investigated. The change from EC to argon photoionization also occurs in 4–6 s but the reverse process requires ∼9 s.
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    URL: http://dx.doi.org/10.1007/BF02271010
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    Detection of ethanol in human body fluids by headspace solid-phase micro extraction (SPME)/capillary gas chromatography (1996)
    Springer
    Chromatographia 43 (1996), S. 393-397 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid-phase micro extraction (SPME) ; Headspace sampling ; Ethanol ; Alcohol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Ethanol has been found extractable from human whole blood and urine samples by headspace solid-phase micro extraction (SPME) with a Carbowax/divinylbenzene-coated fiber. After heating a vial containing the body fluid sample with ethanol, and isobutanol as internal standard (IS) at 70°C in the presence of (NH4)2SO4, a Carbowax/divinylbenzene-coated SPME fiber was exposed in the headspace of the vial to allow adsorption of the compounds. The fiber needle was then injected into a middle-bore capillary gas chromatography (GC) port. The headspace SPME-GC gave intense peaks for both compounds; a small amount of background noises appeared, but did not interfere with the detection of the compounds. Recoveries of ethanol and IS were 0.049 and 0.026% for whole blood, respectively, and 0.054 and 0.085% for urine, respectively. The calibration curves for ethanol showed excellent linearity in the range of 80–5000 mg L−1 for whole blood and 40–5000 mg L−1 for urine; the detection limits for both samples were 20 and 10 mg L−1, respectively. The data on actual determination of ethanol after the drinking of beer are also presented for two subjects.
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    URL: http://dx.doi.org/10.1007/BF02271017
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    Exhibition of the first gas chromatographic work of Erika Cremer and Fritz Prior (1996)
    Springer
    Chromatographia 43 (1996), S. 444-446 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; History of chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In November 1995, theDeutsches Museum, the world's largest technical museum, opened a new branch in Bonn, devoted to achievements after 1945. There, the first gas chromatographic system used by Erika Cremer and Fritz Prior, in 1945–47, in Innsbruck, is exhibited. The new display is described and the early activities of Erika Cremer and her students are summarized.
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    URL: http://dx.doi.org/10.1007/BF02271028
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    Simple extraction of phencyclidine from human body fluids by headspace solid-phase microextraction (SPME) (1996)
    Springer
    Chromatographia 43 (1996), S. 331-333 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid-phase microextraction ; Headspace sampling ; Phencyclidine (PCP) ; Surface ionization detection (SID)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Phencyclidine (PCP) was found to be extractable by headspace solid-phase microextraction (SPME) from human whole blood and urine. Sample solutions were heated at 90°C in the presence of NaOH and K2CO3, and an SPME fiber was exposed in the headspace of a vial for 30 min. Immediately after withdrawal of the fiber, it was analyzed by gas chromatography with surface ionization detection (GC-SID). Recoveries of PCP were approximately 9.3–10.8% and 39.8–47.8% for whole blood and urine samples, respectively. The calibration curve for PCP showed good linearity in the range 2.5–100 ng mL−1 whole blood and 0.5–100 ng mL−1 urine. The detection limits were approximately 1.0 ng mL−1 for whole blood and 0.25 ng mL−1 for urine.
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    Correlations between gas chromatographic retention data of polycyclic aromatic hydrocarbons and several molecular descriptors (1995)
    Springer
    Chromatographia 40 (1995), S. 532-538 
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    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.
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    Relations between pneumatic parameters of ideal gas in a column with uniform permeability (1995)
    Springer
    Chromatographia 41 (1995), S. 15-22 
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    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.
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    Simulation of column efficiency in temperature programmed gas-liquid chromatography (1995)
    Springer
    Chromatographia 41 (1995), S. 37-42 
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    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%.
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    URL: http://dx.doi.org/10.1007/BF02274193
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    Solid phase microextraction using fused silica fibers coated with graphitized carbon black (1995)
    Springer
    Chromatographia 41 (1995), S. 678-684 
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    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.
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    Preparation and gas chromatographic characterisation of 3-bromo-4-(4-methylbenzyloxy)azobenzene stationary phase (1995)
    Springer
    Chromatographia 41 (1995), S. 697-701 
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    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.
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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.
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    Analysis of short chain fatty acids from different intestinal samples by capillary gas chromatography (1995)
    Springer
    Chromatographia 40 (1995), S. 550-556 
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    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.
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    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 
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    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.
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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.
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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 
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    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.
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    Determination of volatiles in spirits using combined stationary phases in capillary GC (1995)
    Springer
    Chromatographia 41 (1995), S. 722-725 
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    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.
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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 
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    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.
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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 
    Details
    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)
    Springer
    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 
    Details
    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)
    Springer
    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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  • 149
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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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  • 150
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269719
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  • 151
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269726
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  • 152
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    Backbone modification of Chirasil-Val: Effect of nonpolar side chains on enantiomer separation in gas chromatography (1995)
    Springer
    Chromatographia 40 (1995), S. 718-723 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Enantiomer separation ; Chiral polysiloxane ; Amino acids ; Physicochemical properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The polysiloxane backbone of the gas chromatography phase Chirasil-Val has been modified by replacing one methyl group per dialkylsiloxy unit by pentyl and hexyl groups, respectively. The new phases offer the advantage of reduced polarities and softening points, while the separation factors (α) of enantiomeric pairs of N,O-trifluoroacetyl amino acid propyl esters show small but intriguing deviations from those determined on Chirasil-Val.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02315143
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  • 153
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    On-line coupling of solid-phase extraction and gas chromatography with atomic emission detection for analysis of trace pollutants in aqueous samples (1995)
    Springer
    Chromatographia 40 (1995), S. 119-124 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Atomic emission detection ; Aqueous samples ; Solid-phase extraction ; Organophosphorus pesticides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An on-line, solid-phase extraction gas chromatography atomic-emission detection (SPE-GC-AED) system has been set up using an on-column interface to transfer 100 μl of desorbing solvent to the GC part of the system. Analytical characteristics such as recovery, precision and linearity of calibration plots were comparable with those of the off-line combination of SPE-GC-AED using organophosphorus pesticides as test compounds. The fully on-line set-up causes a marked improvement in detection because of the quantitative transfer of the analytes from the SPE module to the GC: detection limits are as low as 5–20 ng l−1 for the analysis of 10 ml raw and spiked surface water samples using the phosphorus channel. Detection levels can be further enhanced by processing up to 100 ml samples. The integrated analytical system is robust. The potential of the on-line set up has been demonstrated for the analysis of surface water and waste water.
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    URL: http://dx.doi.org/10.1007/BF02272157
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  • 154
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    Reversed-phase liquid chromatography coupled on-line with capillary gas chromatography use of an anion-exchange membrane to remove an ion-pair reagent from the eluent (1995)
    Springer
    Chromatographia 40 (1995), S. 267-271 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Column liquid chromatography ; On-line coupling ; Ion-exchange membrane ; Ion-pair reagent
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In order to enable the coupling of reversed-phase liquid chromatography (RPLC) with capillary gas chromatography (GC), the performance of an anion-exchange micromembrane device has been studied to remove the ion-pair reagent methanesulphonic acid from an acetonitrile/water LC eluent. The regenerant in the membrane was tetrabutylammonium hydroxide dissolved in acetonitrile/water, which effects an anion-exchange of methanesulphonate ions for regenerant hydroxide ions. The efficiency of the exchange process was found to be 99.9%. This enabled the direct introduction of the LC eluent, free of ions and with the proper acetonitrile/water ratio, into the GC. The applicability of the on-line LC-micromembrane-GC system has been illustrated for the potential drug eltoprazine, which is quantitatively recovered with a coefficient of variation for standard solutions of 3% at the 150 μg/ml analyte level.
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    URL: http://dx.doi.org/10.1007/BF02290356
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  • 155
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    On-line automated sample preparation-capillary gas chromatography for the analysis of plasma samples (1995)
    Springer
    Chromatographia 40 (1995), S. 500-506 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; ASPEC ; Trazodone in plasma ; Method automation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An automated sample preparation module, (the automated sample preparation with extraction columns, ASPEC), was interfaced with a capillary gas chromatograph (GC) by means of an on-column interface. The system was optimised for the determination of the antidepressant trazodone in plasma. The clean-up of untreated plasma was carried out with disposable C18 cartridges, using several washing steps. The analyte was desorbed with methanol, the extract was diluted on-line with buffer and preconcentrated on a PLRP-S trapping column. The trapping column was dried by purging with nitrogen gas. Desorption (phase switching) of the trapping column was carried out with ethyl acetate which was introduced into a retention gap using partially concurrent solvent evaporation conditions. Trazodone was determined by GC with flame ionisation detection (FID). With a 1 ml sample, this resulted in a detection limit for trazodone in plasma of 3 ng/ml. The system showed good linearity and repeatability in the range 0.01–1 μg/ml, thus covering the range of pharmacokinetic/dynamic-to-therapeutic concentrations of trazodone in plasma. Preliminary results for benzodiazepines are promising. They indicate that the use of a selective detector such as the nitrogen/phosphorus detector, is to be recommended.
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    URL: http://dx.doi.org/10.1007/BF02290259
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    A simple gas chromatographic method for the analysis of oxygenates in gasoline (1995)
    Springer
    Chromatographia 40 (1995), S. 607-610 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Packed column separations ; C1−C4 alcohols ; Ethers ; Gasoline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A number of oxygenated compounds such as C1−C4 alcohols, methyl tert-butyl ether (MTBE), and tertamyl methyl ether (TAME) are increasingly being used in gasoline as octane boosters and to reduce vehicular emissions. Monitoring of individual oxygenates in gasoline is important for quality control and regulatory purpose. Although, several analytical methods based on gas chromatography have been reported, a need was still felt to develop a simple and cost effective method of analysis. In this paper, a packed column gas chromatographic method is described for the analysis of C1−C4 alcohols, MTBE and TAME over a wide concentration range (2–20% V/V) in gasoline. The method involves determination of alcohols and ethers separately on two different columns. The alcohols are determined on a 20 ft column packed with poly(ethylene glycol) 400 as a stationary phase while the ethers are analysed on a 20 ft OPN-Poracil C column. The analysis of alcohols on poly(ethylene glycol) 400 column also provides data on aromatic components of gasoline.
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    URL: http://dx.doi.org/10.1007/BF02290276
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    Comparison of correlation equations for the prediction of gas chromatographic separation of alkylbenzenes (1995)
    Springer
    Chromatographia 41 (1995), S. 183-186 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Correlation equation ; Alkylbenezenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A detailed statistical analysis, comparing the validity of the best literature recommended equations for prediction of retention indices of alkylbenzenes on squalane and methylsilicone stationary phases with the unified retention index concept, is presented. A comparison with literature sources shows that the unified retention index provides the smallest residual error. Hence, it can be applied for prediction purposes.
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    URL: http://dx.doi.org/10.1007/BF02267952
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    Ring opening of cyclohexane over ZSM-zeolites followed by reversed-flow gas chromatography (1995)
    Springer
    Chromatographia 41 (1995), S. 227-235 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Reversed-flow technique ; Catalysis ; Ring opening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Kinetic parameters for the ring opening of cyclohexane over modified ZSM-5 zeolites can be measured simultaneously under non-steady state conditions using reversed-flow gas chromatography. At relatively low temperatures, the main product detected and measured was propene. The mathematical relations used for the calculation of adsorption-desorption rate constants, surface reaction rate constants and adsorption equilibrium constants for the reactant cyclohexane are different from previously studied catalytic reactions, owing to the different experimental arrangement for feeding the catalytic bed. The diffusion bands obtained experimentally for reactant or product are described by the sum of two or three exponential functions of time, respectively. From the exponential coefficients of time and the pre-exponential factors, all determined by simple PC programs, the above kinetic parameters are calculated.
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    URL: http://dx.doi.org/10.1007/BF02267960
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  • 159
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    Gas chromatography on a self-associating component of a binary phase. Retention model by formal analogy with conductance of electrolytes in dilute solution (1995)
    Springer
    Chromatographia 41 (1995), S. 221-226 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Binary stationary phase ; Self-associating phase components ; Retention model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The dependence of specific retention by a binary stationary phase in GC can be expressed as the sum of the products of the specific retention of the pure components times their respective volume fractions. In this study, however, one component has a site, which is not only mainly responsible for the selectivity, but also participates in strong self-association. This requires introduction of a concentration-dependent factor (μx) in the corresponding term of the equation correlating Vg mix x with x. In the GC resolution of N-trifluoroacetyl-amino acid isopropyl esters on a binary phase, N-lauroyl-L-amino t-butyl amide-squalane, data for the values of μx were obtained. Adapting a previously developed LC retention model to the above GC data, an equation was derived for the dependence of μx on the weight fraction (x) of the selector, namely μx=√1/x. This relationship permits calculation of retention volumes on the binary phase for a given x, as well as corresponding resolution coefficients of enantiomeric amino acid derivatives with generally excellent agreement with experiment. The chirality of the system is not relevant to application of the equation.
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    URL: http://dx.doi.org/10.1007/BF02267959
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    Fast headspace analysis with short microcapillary columns (1995)
    Springer
    Chromatographia 41 (1995), S. 419-423 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace analysis ; Microcapillary columns ; Short columns ; Volatile compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method of analysis using headspace gas chromatography with microcapillary columns is proposed. Small diameter (50 μm I.D.) fused-silica capillary columns with non-extractable SE-54 and PS-255 polysiloxane stationary phases were used for the analysis of low boiling organic compounds. The small diameter columns possess the usual very high efficiency so that the method can be employed for the headspace analysis of complex mixtures. The use of short microcolumns reduces the analysis times in comparison to conventional capillary columns. Good performances were obtained in the analysis of volatile compounds in some lemon essential oil, perfumes, and water samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02318616
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    Capillary gas chromatography of aromatic bicyclic and tricyclic spiro ketones (1995)
    Springer
    Chromatographia 41 (1995), S. 594-598 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Capillary column ; Bicyclic spiro ketones ; Tricyclic spiro ketones ; Retention index at different temperatures ; Retention vs stationary phase polarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of some aromatic bicyclic and tricyclic spiro ketones on fused silica capillary columns coated with polydimethylsiloxane, cyanopropylmethylsiloxane and poly(ethylene glycol) stationary phases was investigated. Retention indices were determined at two temperatures in order to enable understanding of the compounds' chromatographic behaviour. The respective standard deviation values were 0.8, 0.5 and 0.3 index units. The influence of the polarity of the stationary phases on the chromatographic retention of these cyclic spiro ketones is discussed.
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    URL: http://dx.doi.org/10.1007/BF02269725
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