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  • Analytical Chemistry and Spectroscopy  (29)
  • 42.75
  • 2000-2004  (2)
  • 1990-1994  (27)
  • 1
    Electronic Resource
    Electronic Resource
    Variable splitter for regulation of the solvent evaporation rate in the coupling of liquid chromatography with gas chromatography (1990)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 13 (1990), S. 405-409 
    Details
    ISSN: 0935-6304
    Keywords: Coupled LC-GC ; Retention gap ; Variable splitter ; Partially concurrent solvent evaporation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A system is described which accelerates the solvent evaporation rate in the retention gap. The evaporation is due to a saturation effect of the carrier gas stream, and a considerable increase in evaporation rate is obtained by inserting a split outlet between the retention gap and the capillary separation column in the gas chromatograph. By varying the backpressure of the spliter device, the flow rate through the retention gap can be adjusted and so too the evaporation rate. The evaporation process was monitored by inserting a dectecter in the split outlet line. The technique was applied to the on-line LC trace enrichment/GC analysis of water containing a mixture of polycyclic aromatic hydrocarbons.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240130604
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of planar chlorobiphenyls in animal fat (1990)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 13 (1990), S. 797-802 
    Details
    ISSN: 0935-6304
    Keywords: Capillary GC ; GPC and HPLC sample preparation ; Automation ; Planar chlorobiphenyls ; Horse fat ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The occurrence of the highly toxic non-ortho substituted (planar) chlorobiphenyls (CBs) at low levels in wildlife, (human) fat, and fish generates the need for a routine analytical procedure. The use of a fully automated system for the separation of planar and non-planar CBs, consisting of a gel permeation chromatography system, a sample preparation system employing extraction columns, and a porous graphitic carbon HPLC column is described, and tested with horse fat. Gas chromatography on capillary columns, with electron-capture or high resolution mass spectrometric detection, is used for quantitation of the CBs.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240131202
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  • 3
    Electronic Resource
    Electronic Resource
    Microcolumn liquid chromatography of the enantiomers of organophosphorus pesticides with thermionic and ultraviolet detection (1991)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 14 (1991), S. 460-464 
    Details
    ISSN: 0935-6304
    Keywords: Micropacked liquid chromatography ; Enantiomer separation ; HPLC-TID ; Organophosphorus pesticides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Microcolumn liquid chromatography (micro-LC) of some chiral organophosphorus pesticides has been studied using Chiralcel OD columns and simultaneous ultraviolet (UV) and phosphorus selective detection, the latter by means of a micro-UV cell coupled on-line to a thermionic detector (TID). Micro-LC showed a ca. 5-fold improved separation impedance, a ca. 1.8-fold increased column permeability, and greater inertness compared with conventional LC.By using the TID, organophosphorus pesticides could be satisfactorily determined at trace levels, the detection limit being 4 pg/s of phosphorus. The response of the micro-LC-TID system is linear in the range of 0.05-20 ng (r = 0.9994).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240140708
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  • 4
    Electronic Resource
    Electronic Resource
    Selective and sensitive detection of organic contaminants in water samples by on-line trace enrichment-gas chromatography-mass spectrometry (1993)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 16 (1993), S. 397-403 
    Details
    ISSN: 0935-6304
    Keywords: Coupled LC-GC-MS ; Aqueous sample ; s-Triazine Herbicides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Liquid chromatographic (LC) type trace enrichment is coupled online with capillary gas chromatography (GC) with mass spectrometric (MS) detection for the analysis of aqueous samples. A volume of 1-10 ml of an aqueous sample is preconcentrated on a trace-enrichment column packed with a polymeric stationary phase. After cleanup with HPLC-grade water the precolumn is dried with nitrogen and subsequently desorbed with ethyl acetate. A fraction of 60 μl is introduced on-line into a diphenyltetramethyldisilazane-deactivated retention gap under partially concurrent solvent evaporation conditions and using an early solvent vapor exit. The analytes are separated and detected by means of GC-MS. The potential of the LC-GC-MS system for monitoring organic pollutants in river and drinking water is studied. Target analysis is carried out with atrazine and simazine as model compounds; the detection limits achieved under full-scan and multiple ion detection conditions are 30 pg and 5 pg, respectively. Identification of unknown compounds (non-target analysis), is demonstrated using a river water sample spiked with 168 pollutants varying in polarity and volatility.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240160703
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  • 5
    Electronic Resource
    Electronic Resource
    Fully automated water analyzer based on on-line solid phase extraction-gas chromatography (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 5 (1993), S. 303-315 
    Details
    ISSN: 1040-7685
    Keywords: capillary GC ; solid phase extraction ; membrane disks ; water samples ; automation ; nitrogen-phosphorus detection ; mass selective detection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An automated procedure for the analysis of aqueous samples by membrane disk extraction coupled on-line to capillary gas chromatography (GC) is presented. Organophosphorus pesticides are preconcentrated from aqueous samples on three 0.5 mm thick, 4.0 mm diameter XAD-2 membrane extraction disks which are mounted in a polymer holder for use in a PROSPEKT sample processor. The layers are dried by a stream of nitrogen (30 min at ambient temperature). Desorption of the analytes is carried out with ethyl acetate which is directly introduced into a retention gap under partially concurrent solvent evaporation conditions, using an early solvent vapor exit. The method is a fully software-controlled automated system, and includes sample preparation, sample transfer and GC analysis. The final analysis is carried out by GC with nitrogen-phosphorus (NPD) or mass-selective detection. The technique is applied to the determination of a series of organophosphorus pesticides in tap water and water from European rivers. With a sample volume of only 2.5 mL, the detection limits achieved with the NPD were 20-50 ng L-1 in tap water and 20-100 ng L-1 in river water.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mcs.1220050403
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  • 6
    Electronic Resource
    Electronic Resource
    Verification of nonproduction of chemical warfare agents: II. Large volume injections in microcolumn liquid chromatography using flame photometric detection (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 4 (1992), S. 477-483 
    Details
    ISSN: 1040-7685
    Keywords: micro-LC ; large-volume injections ; flame photometric detection ; organo-phosphates ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The sensitivity and separation performance of microcolumn liquid chromatography coupled with a flame photometric detector were considerably improved by the direct injection of large sample volumes (approximately 10 μL) and by peak compression. Extremely narrow peaks can be obtained by adding displacers such as hydrochloric acid (ion-exchange mode) or n-butanol (reversed-phase mode) to the sample.The system was used for the determination of ethyl methylphosphonic acid, isopropyl methylphosphonic acid, and pinacolyl methylphosphonic acid which are the hydrolysis products of the super-lethal nerve agents VX, sarin, and soman, respectively, and of the final degradation product, methylphosphonic acid. The detection limits for the alkyl methylphosphonic acids and sarin in water were 1-20 ppb.Two examples were used to demonstrate the practicality of the present procedure. Sarin and the much more polar isopropyl methylphosphonic acid were simultaneously determined in a spiked surface water sample used for verification studies. Low-ppb levels of phosphorous acid were identified in mustard gas.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mcs.1220040603
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  • 7
    Electronic Resource
    Electronic Resource
    Coupling of column liquid chromatography and thermospray mass spectrometry via phase-system switching with an ion-exchange trapping column (1992)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 21 (1992), S. 305-314 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A benzenesulphonic acid-type cation exchanger (pKa 〈 1) is used as trapping-column material in a phase-system switching for the on-line coupling of column liquid chromatography and thermospray mass spectrometry. Phase-system switching is used to remove non-volatile constituents from the mobile phase, so that eluents containing non-volatile buffers and ion-pairing agents can be used without contaminating the mass spectrometer. The total analytical system is optimized using four benzalkonium test compounds (quaternary ammonium compounds). The reversed-phase separation of the test compounds as well as the parameters involved in the sorption on and desorption from the trapping column are studied. Important parameters during sorption are the concentration of the phosphate buffer and the percentage of acetonitrile in the mobile phase. During desorption of the test compounds from the ion-exchanger the percentage of acetonitrile in the desorption eluent and the pH are the most important factors. As an example, the analysis of domiphen in nasal drops is shown.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200210607
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  • 8
    Electronic Resource
    Electronic Resource
    The determination of cyclophosphamide and its metabolites in blood plasma as stable trifluoroacetyl derivatives by electron capture chemical ionization gas chromatography/mass spectrometry (1994)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 23 (1994), S. 149-158 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described for the determination of the antitumour drug cyclophosphamide and six stable metabolites in plasma of cancer patients, namely dechloroethyl-cyclophosphamide, 4-keto-cyclophosphamide, carboxy-phosphamide, alcophosphamide, nor-nitrogen mustard and the N-chloroethyl-1,3-oxazolidine-2-one, as methyl and/or trifluoroacetyl derivatives by single ion monitoring gas chromatography/mass spectrometry, mostly in the electron capture chemical ionization mode. The isolation of most metabolites was performed by solid-phase C-18 extraction in weakly acidic medium. The phosphoramide mustard isolated under these conditions decomposes readily to the nor-nitrogen mustard during derivatization. The original nor-nitrogen mustard and the chloroethyl-1,3-oxazolidine-2-one were isolated by liquid extraction with ethyl acetate in alkaline medium. Recoveries of 75-99% were measured using spiked blank plasma samples. Quantitation of metabolites in patient plasma samples was performed using two sets of calibration curves for the concentration ranges of 1-100 ng and 0.1-10 μg of metabolite per millilitre of original plasma.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200230306
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  • 9
    Electronic Resource
    Electronic Resource
    Packed capillary supercritical fluid chromatography of organophorus pesticides: Selective detection and applications (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 6 (1994), S. 55-62 
    Details
    ISSN: 1040-7685
    Keywords: supercritical fluid chromatography ; packed capillary columns ; thermionic detection ; organophosphorus pesticides ; vegetable extracts ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Packed capillary supercritical fluid chromatography coupled with thermionic detection was used for the selective determination of nineteen organophosphorus pesticides in vegetable extracts. The chromatographic behavior of some pesticides was studied using seven different stationary phases. Addition of an organic modifier to carbon dioxide was needed to improve peak shape and reduce retention. Quantitation of organophosphorus pesticides in vegetable extracts showed good linearity. Extraction was performed in a one-step extraction procedure using a water-miscible solvent (acetone) and an organic solvent with limited water capacity (dichloromethane). Under these conditions a wide range of both polar and apolar pesticides can be recovered from vegetable extracts down to the 3-25 μg kg-1 level. The recoveries found ranged from 35 to 95% depending on the polarity of the pesticides.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mcs.1220060111
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  • 10
    Electronic Resource
    Electronic Resource
    On-line post-column Diels-Alder derivatization for the determination of vitamin D3 and its metabolites by liquid chromatography/thermospray mass spectrometry (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 22 (1993), S. 621-632 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Liquid chromatography/thermospray mass spectrometry (LC/TSP MS) has been used for the determination of vitamin D3 and some of its metabolites, i.e. 1α(OH) vitamin D3, 25(OH) vitamin D3, 1α,25(OH)2 vitamin D3 and 24,25(OH)2 vitamin D3, using positive and negative ion detection. Using these two modes positional isomers can be identified. Detection in the negative ion mode was preferred because of the slightly higher sensitivity. The limits of detection, using multiple ion detection, are 50-100 nM (6-12 pmol injected). On-line post-column derivatization based on [4 + 2] cyclo-addition (Diels-Alder reaction) proceeds within 1 min at room temperature. If this step is included in LC/TSP MS, the detection limits of the analytes can be improved 7-70-fold depending on the analyte tested. The best results (detection limits down to 1 nM, i.e. 0.12 pmol injected) are obtained with discharge ionization in the negative ion mode.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200221102
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