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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 3 (1980), S. 545-550 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, fused silica columns ; Selective detectors: TSD, ECD, FPD ; POTW sludge extracts ; Effluent splitter ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Combination of various GC detectors by using a Varian effluent splitter with glass capillary columns has been found to be a rapid procedure for profiling organics extracted from sludges and river sediments. The selectivity and the increased sensitivity of the thermionic nitrogen-phosphorus detector (TSD), the electron capture detector (ECD), and the flame photometric detector (FPD) over the flame ionization detectors (FID) or mass spectrometers allow the detection of compounds present at trace levels without need for extensive sample cleanup. Furthermore, the combination of two selective detectors may supplement the information with regard to the chemical functionalities required for structure elucidation.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Atomic emission detector ; Organotin compounds ; Organolead compounds ; Organomercury compounds ; Grignard derivatization ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As part of a continuing evaluation of new analytical and sample preparation techniques conducted by the US Environmental Protection Agency (EPA), the use of capillary gas chromatography with atomic emission detection (GC-AED) for the simultaneous determination of organotin, organolead, and organomercury compounds in environmental samples was investigated. Pentylmagnesium bromide was used to pentylate ionic organotin, organolead, and organomercury compounds; the pentyl derivatives were then separated by GC and determined by AED. Several important GC-AED parameters, including the type of injector inlet, carrier gas flow rate, and helium make-up gas flow rate, were optimized for the simultaneous determination of these organometallic compounds. Their minimum detectable concentrations were approximately 1.0 to 2.5 ng/mL using a 0.5-μL on-column injection. The calibration curves exhibited good linearity between 2.5 and 2500 ng/mL for organotin and organolead compounds, and between 2.5 and 10000 ng/mL for organomercury compounds.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0935-6304
    Keywords: Capillary GC ; Atomic emission detector ; Supercritical fluid extraction ; Organotin compounds ; Complexation ; Grignard derivatization ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The extraction of six tetraalkyltin and seven ionic organotin compounds from spiked topsoil samples with supercritical carbon dioxide and carbon dioxide modified with 5 percent methanol was investigated. Analysis of the soil extracts was performed by gas chromatography with atomic emission detection. Retention times, minimum detectable concentrations, and detector linear ranges are included for nine organotin compounds (seven of the nine compounds were derivatized with n-pentylmagnesium bromide prior to gas chromatographic analysis). A 23 factorial experimental design was used to study the effect of three variables (pressure, temperature, and extraction time) on compound recovery. The results indicate that the tetraalkyltin compounds are extracted from topsoil samples with recoveries ranging from 90 to 110 percent. Recoveries for the ionic organotin compounds ranged from 50 to 75 percent for trimethyltin chloride, triethyltin bromide, and tributyltin iodide; they were below 20 percent for dimethyltin dichloride, dibutyltin dichloride, diphenyltin dichloride, and butyltin trichloride. When sodium diethyldithiocarbamate was added to the soil samples prior to extraction, followed by extraction with carbon dioxide modified with 5 percent methanol, recoveries ranged from 70 to 90 percent for trimethyltin chloride, triethyltin bromide, dimethyltin dichloride, tributyltin iodide, and dibutyltin dichloride; recoveries were approximately 40 percent for butyltin trichloride and diphenyltin dichloride.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 231-236 
    ISSN: 0935-6304
    Keywords: Gas chromatography/mass spectrometry (GC/MS) of oxindole alkaloids ; HPLC/MS of oxindole alkaloids ; Supercritical fluid extraction ; Oxindole alkaloids ; Uncaria Tormentosa ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Supercritical fluid extraction of oxindole alkaloids from Uncaria Tormentosa is described. The extraction was performed with supercritical carbon dioxide alone and with supercritical carbon dioxide modified with 10% metanol, and the extracts were analyzed by GC/MS and HPLC/MS.
    Additional Material: 8 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 487-492 
    ISSN: 0935-6304
    Keywords: Gas chromatography with thermionic-selective detection ; Solid-phase microextraction ; Organophosphorus pesticides ; Water analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper describes the extraction of 49 organophosphorus pesti-cides (OPPs) from water samples using solid-phase microextraction (SPME). Three fibers, including a 15-μm XAD-coated fiber, a 85-μm polyacrylate-coated fiber, and a 30-μm polydimethylsilox-ane-coated fiber (PDMS), were evaluated here. The effects of stirring and the addition of NaCl to the sample were examined for the polyacrylate-coated fiber. The precision of the technique was examined for all three fibers and the extraction kinetics were investigated using the XAD- and polyacrylate-coated fibers. With some exceptions, the XAD- and polyacrylate-coated fibers performed better than the PDMS-coated fiber. The superiority of the XAD-nd polyacrylate-coated fiber. The superiority of the XAD- and polyacrylate-coated fibers over the PDMS-coated fibers can be attribuibuted to the aromatic functionalities of the XAD and the polar functionalities in the polyacrylate. The relatively high percent RSDs indicate that the SPME technique needs to be further refined before it can be used for anything other than screening. A more effective form of agitation than mechanical stirring may be neccessary to reduce variability and achieve a faster equilibrium between the sample and the SPME fiber.
    Additional Material: 8 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 14 (1991), S. 601-607 
    ISSN: 0935-6304
    Keywords: Nitroaromatic compounds ; Fused silica open tubular column ; Dual-column/dual-detector GC system ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thirty five nitroaromatic compounds (currently listed in EPA Method 8091) and 1,4-naphthoquinone have been separated on DB-5-DB-1701 and SPB-5-SPB-1701 column pairs, which were in each case connected to an inlet splitter and separate electron capture detectors. Retention times are included for 21 additional compounds evaluated for their suitability as internal standards and/or surrogate compounds for incorporation into Method 8091. Method reproducibility and linearity are discussed, and results are presented for extracts of two real samples spiked with the 35 nitroaromatic compounds and 1,4-naphthoquinone and analyzed using the dual-column-dual-detector arrangement.
    Additional Material: 4 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 319-328 
    ISSN: 0935-6304
    Keywords: Organochlorine pesticides ; Fused silica open tubular column ; Dual-column, dual-detector gas chromatographic system ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Forty five organochlorine pesticides (currently listed in EPA Method 8081A) have been chromatographed on DB-5/DB-1701 and SPB-5/SPB-1701 column pairs which were in each case connected to an inlet splitter and separate electron capture detectors. Thirteen additional compounds were evaluated for their suitability as internal standards or surrogate compounds for incorporation into Method 8081A. Method reproducibility and linearity are discussed, and results are presented for extracts of six real samples spiked with fifteen organochlorine pesticides and analyzed using the dual-column, dual-detector arrangement.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 16 (1993), S. 717-720 
    ISSN: 0935-6304
    Keywords: Capillary zone electrophoresis (CZE) ; Microwave-induced helium plasma atomic emission detector ; On-line capillary zone electrophoresis with atomic emission detection ; Organotin compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We report a feasibility study on using a microwave-induced helium plasma atomic emission detector (MIP-AED) as an on-line detector in capillary zone electrophoresis (CZE). To couple CZE to MIP-AED, we used an ion exchange membrane capillary to connect the separation capillary to the interfacing capillary. The outlet end of the interfacing capillary was placed directly in the discharge tube of the MIP-AED system. The electroosmotic flow generated in the separation capillary carried the analytes and the electrolyte buffer solution through the interfacing capillary into the MIP-AED discharge tube where the analytes were detected. The performance of the CZE/MIP-AED system was evaluated with trimethyltin chloride, dimethyltin dichloride, n-propanol, and 2-butanone. The preliminary results indicate that the MIP-AED can be used in CZE to provide element-specific detection for target analytes.
    Additional Material: 6 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 247-256 
    ISSN: 0935-6304
    Keywords: Gas chromatography with electron capture detection ; Solid phase microextraction ; Organochlorine pesticides ; Water analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper describes the extraction of 20 organochlorine pesticides (OCPs) from water samples using solid-phase microextraction (SPME). Three fused-silica fibers coated or bonded with polydimethylsiloxane (PDMS) of different film thicknesses (20-, 30-, and 100-μm) were evaluated. The extraction time, the effects of stirring and addition of NaCl to the aqueous sample, the linear range and the precision of this technique, and the effect of carryover were examined for 20 analytes and are presented here. A comparison with results using conventional liquid-liquid extraction demonstrate that the SPME technique is well suited as a fast screening technique for OCPs in water samples.
    Additional Material: 6 Ill.
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  • 10
    ISSN: 0935-6304
    Keywords: Vinyl chloride ; Ion mobility spectrometry ; GC/IMS ; Chemical field screening ; Environmental chemical analysis ; Chemical analysis of air ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The objective of this research was to evaluate, in the laboratory, the potential of gas chromatography/ion mobility spectrometry (GC/IMS) for monitoring vinyl chloride and other organic compounds in air samples in the field. It was determined that GC/IMS has the potential to directly detect vinyl chloride in air at the 2 ppbv level, and when concentrated on an adsorbent trap from a 1 L sample of air, detection could be lowered to the 0.02 ppbv level. From a comparative investigation of 18 EPA priority pollutants and 34 common vapor-phase organic compounds, many compounds were found to provide a more sensitive response in IMS than vinyl chloride, indicating that GC/IMS would be broadly applicable to the direct detection of vapor-phase organics in air.Operating parameters including drift gas, spectrometer temperature, and sample-inlet position were evaluated and discussed with respect to sensitivity and resolution. High temperature dramatically increased sensitivity to vinyl chloride. Vinyl chloride was shown to produce both negative and positive ion mobility spectra, with the negative-mode spectra resulting from electron-capture dissociation of the vinyl chloride. The limit of detection for vinyl chloride was found to be 7 pg/s. Limits of detection for 18 EPA priority pollutants were determined and compared to vinyl chloride. The responses of 34 other vapor-phase organic compounds were also compared to that of vinyl chloride. Non-selective, positive-ion detection of 30 of the 34 compounds was demonstrated along with selective, electron-capture-type detection of 29 of them. Chloride-specific and bromide-specific detection illustrated the advantages of selected-ion monitoring in IMS.
    Additional Material: 8 Ill.
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