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  • Chemistry  (144)
  • Gas chromatography  (10)
  • 1995-1999  (105)
  • 1935-1939  (46)
  • 1
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272157
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  • 2
    Electronic Resource
    Electronic Resource
    Spektroskopische Untersuchungen zur Acidität von Dithiophosphorsäure-O,O′-estern in unpolaren, aprotischen Lösungsmitteln (1995)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 337 (1995), S. 245-249 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Spectroscopic Investigations on the Acidity of O,O′-Dithiophosphoric Acid Esters in Nonpolar Aprotic Solvents
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19953370153
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  • 3
    Electronic Resource
    Electronic Resource
    Data correlation in on-line solid-phase extraction-gas chromatography-atomic emission/mass spectrometric detection of unknown microcontaminants (1998)
    Springer
    Chromatographia 48 (1998), S. 273-283 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Atomic emission and MS detection ; Solid-phase extraction ; Aqueous samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A procedure is described for the (non-target) screening of hetero-atom-containing compounds in tap and waste water by correlating data obtained by gas chromatography (GC) using atomic emission (AED) and mass selective (MS) detection. Solid-phase extraction (SPE) was coupled on-line to both GC systems to enable the determination of microcontaminants at the 0.02–1 μg L−1 level in 7–50 mL of aqueous sample. The screening was limited to compounds present in at least one heteroatom-selective GC-AED trace above a predetermined concentration level. These compounds were identified by their partial formulae (AED) and the corresponding mass spectra, which were obtained from the GC-MS chromatogram via the retention index concept. The potential of the approach was demonstrated by the identification of target compounds as well as all unknowns present in tap and waste water above the predetermined threshold of 0.05 μg L−1 (tap water) or 0.5 μg L−1 (waste water).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467683
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  • 4
    Electronic Resource
    Electronic Resource
    On-line sample treatment—capillary gas chromatography (1998)
    Springer
    Chromatographia 47 (1998), S. 313-345 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Sample pretreatment ; Coupling on-line to capillary GC ; Robotization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Sample pretreatment is often the bottleneck of a tracelevel analytical procedure. In order to increase performance, increasing attention is therefore being devoted to combining sample pretreatment on-line with the separation technique that has to be used. In the present review, a variety of procedures in use today for sample treatment coupled on-line to capillary gas chromatography (GC) is briefly discussed. Special attention is devoted to coupled-column techniques such as SPE-GC and LC-GC (SPE, solid-phase extraction; LC, column liquid chromatography) which are topics of much current interest, also because of their frequent use in so-called hyphenated systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466538
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  • 5
    Electronic Resource
    Electronic Resource
    On-line solid-phase extraction-gas chromatography-ion trap tandem mass spectrometric detection for the nanogram per liter analysis of trace pollutants in aqueous samples (1997)
    Springer
    Chromatographia 44 (1997), S. 372-380 
    Details
    ISSN: 1612-1112
    Keywords: Solid-phase extraction ; Gas chromatography ; Ion trap tandem mass spectrometry ; Water samples ; Environmental analysis ; Pesticides ; Bromide ; Nitrite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary On-line solid-phase extraction-gas chromatographyion-trap tandem mass spectrometry (SPE-GC-MS/MS) has been used for the trace-level determination of polar and apolar pesticides. The SPE-GC interface, an Autoloop 2000, was operated at an injection temperature of 90°C which permitted the determination of thermolabile pesticides such as carbofuran and carbaryl. Rectilinear calibration curves were obtained for the analytes tested over a range of 0.1–500 ng L−1, using a sample volume of 10–100 mL for enrichment on an SPE cartridge packed with styrene-divinylbenzene copolymer. The detection limits for the pesticides were in the 0.01–4 ng L−1 range. For a number of pesticides acceptable tandem mass spectra were obtained at levels as low as 0.1 ng L−1 level in real-life water samples. As a demonstration of the applicability of this technique for inorganic anions, bromide and nitrite were converted into 4-bromoacetanilide and 2-phenylphenol, respectively. The reaction products were pooled and subjected to simultaneous analysis by the present method using full-scan mass spectrometric detection. The detection limits were 0.3 and 2 ng L−1, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466313
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  • 6
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290356
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  • 7
    Electronic Resource
    Electronic Resource
    Chromatographic determination of phosphine (PH3) and hydrogen sulfide (H2S) in the headspace of anaerobic bacterial enrichments using flame photometric detection (1995)
    Springer
    Chromatographia 40 (1995), S. 399-403 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Phosphine ; Flame photometric detection ; Anaerobic bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A gas chromatographic method is presented which distinguishes phosphine from hydrogen sulfide and other possible headspace gases of anaerobic microbial cultures. In anaerobic cultures spiked with phosphine, this gas is recovered in the liquid and gaseous phase down to 10 pg per ml of gas or liquid. No biogenically produced phosphine was found. Phosphine in amounts as small as 30 ng per 1 can be stored for several days in glass bottles covered with rubber septa, filled with nitrogen, in the presence or absence of water or of an anaerobic bacterial culture. Due to the selectivity of the detector and the retention characteristics of the porous layer open tubular polymer column alkanes, alkenes and organosulfur compounds routinely found in anaerobic bacterial headspaces do not interfere with the analytical quantification of phosphine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269902
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  • 8
    Electronic Resource
    Electronic Resource
    4-(1-Methyl-2-sulfamoylvinyl)pyrazoles by Ring Transformation of 1,1-dioxo-2H-1,2-thiazine-4-carbaldehydes with hydrazinesDedicated to Professor H. G. O. Becker on the Occasion of his 75th Birthday (1997)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 339 (1997), S. 277-283 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As masked 1,3-dicarbonyl compounds, 1,1-dioxo-2H-1,2-thiazine-4-carbaldehydes (2a-e, 7) undergo ring transformations with nucleophilic hydrazines to produce 4-[1-methyl-2-(arylsulfamoyl)vinyl]pyrazoles (9a-i). For 9h, an X-ray structural analysis is reported. With less nucleophilic semicarbazide and p-nitrophenylhydrazine the hydrazones (11a, b) were isolated. The carbaldehydes 2a-e, 7 and 8a, b were synthesized by formylation of the 1,1-dioxo-2H-1,2-thiazines 1a-e, 5 and 6a, b with dichloromethyl methyl ether/TiCl4. In the case of 1a-e mixtures of 4- and 6-carbaldehydes (2a-e/3a-e) were obtained, which, however, could be used for the synthesis of pyrazoles.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19973390149
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  • 9
    Electronic Resource
    Electronic Resource
    Struktur des basischen Zink-O,O′-2-ethylhexyldithiophosphats in unpolar, aprotischen Lösungsmitteln (1995)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 337 (1995), S. 647-654 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structure of Basic Zinc-O,O′-2-ethylhexyldithiophosphates in Apolar Aprotic SolventsA sample of technically used Zinc-O,O′-2-ethylhexyldithiophosphate enriched by basic Zinc-O,O′-2-ethylhexyldithiophosphates (i-C8-ZnDTP) was investigated in aprotic apolar solvents by integral and structure specific analytical methods. The results let us suppose that the structure of basic i-C8-ZnDTP in apolar aprotic solvents can be described by an Zn3-complex of type ZnO(ZnDTP)2.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.199533701138
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  • 10
    Electronic Resource
    Electronic Resource
    Bis-(1-chlor-3-phenoxy-prop-2-yl)-sulfane - Nucleophile Substitution und Regiochemie, Diastereomerentrennung und -zuordnung. Synthese diastereomerenreiner Trithiacyclen (1996)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 327-336 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis-(1-chloro-3-phenoxy-prop-2-yl)-sulfanes - Nucleophilic Displacement and Regiochemistry. Separation and Assignment of Diastereomers. Synthesis of Diastereomerically Pure TrithiacyclesThe title compounds 1 were substituted by a series of O-, N- and S-nucleophiles (H2O solvolysis, AgOAc, NaN3, KSCN, NaSPh, thiourea). A strong tendency to β-elimination of HCl depending on the kind of the attacking nucleophile was found. In most cases no regioisomerization could be detected in the isolated products of the nucleophilic displacement. Best results were obtained with sulfur nucleophiles. The separation of the diastereomeric mixture of the p-kresyl derivative 1b into the individual diastereomers 1bA and 1bB in a preparative scale was achieved. These 3-thia-1,5-dichlorides and several products of substitution could be assigned to the meso- or (±)-form by examination of the stereochemistry and symmetry of the corresponding sulfoxides.The 1,5-dimercapto derivatives 8 are convenient as structural units for the synthesis of diastereomerically pure cis- or trans-disubstituted trithiacycles e.g. 15bA, 15bB. The (±)-form of the 4,6-disubstituted 2,5,8-trithia[9]-(2,6)-pyridinophane 16bA was characterized by X-ray crystal structure determination.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19963380165
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