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  • Large volume injection  (5)
  • Natural gas analysis  (2)
  • PAHs  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 17 (1994), S. 373-389 
    ISSN: 0935-6304
    Keywords: GC ; Natural gas analysis ; Sulfur components ; Selective enrighment ; Sulfur selective detection ; Calibration ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: More stringent environmental regulations as well as higher demands presently being imposed on the sulfur content of natural gas feed-stocks for chemical processes necessitate the development of new analytical procedures for sulfur determination in natural gas. Only analytical procedures based on gas chromatography can meet the sensitivity and accuracy requirements dictated by environmental regulation institutions and modern chemical industry. The complexity of the natural gas matrix as well as the extremely low concentration levels at which the sulfur species occur make the development of these analytical methods a true challenge. In this review the three steps common for analytical methods for trace analysis in complex matrices, i.e. pretreatment, chromatographic separation, and detection, are discussed in detail. Possible methods for calibration of the system are discussed in the final section.Various techniques to determine sulfur in natural gas are described. Depending on the application, the most suitable system has to be selected. For example, for on-line application in a hazardous area a simple and rugged system is required, i.e. a simple gas chromatograph with a flame photometric detector, while for laboratory application a more complex instrument including preconcentration, column switching, and more exotic detection systems could be more suitable. Therefore it is crucial to define the requirements of the instrument at an early stage and use the information in this review article to develop/select a dedicated instrument/procedure for the problem at hand.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 69-79 
    ISSN: 0935-6304
    Keywords: Large volume injection ; PTV injector ; Water analysis ; River sediment ; Pesticides ; Polycyclic aromatic hydrocarbons (PAHs) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Temperature programmable (PTV) injectors with packed widebore (ca. 3.5 mm i.d.) liners are used for large volume injection in capillary gas chromatography with the aim to simplify and/or improve off-line sample pretreatment proecdures. A simple procedure for optimization of large volume PTV injection is described. The system performance, i.e. linearity and repeatability, is evaluated for polar nitrogen/phosphorus containing pesticides (PTV-GC-NPD) and organochlorine pesticides (PTV-GC-ECD) in river water extracts as well as for polycyclic aromatic hydrocarbons (PAHs) in river sediment (PTV-GC-MS).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 16 (1993), S. 413-418 
    ISSN: 0935-6304
    Keywords: On-line extraction-GC ; Phase-switching ; Open-tubular traps ; Stationary phase swelling ; Large volume injection ; PTV ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The applicability of open-tubular trapping columns for on-line extraction-capillary GC analysis is evaluated. The extraction step involves sorption of the analytes from water into the stationary phase of an open-tubular column, removal of the water by purging the trap with nitrogen, and desorption of the analytes with an organic solvent. The effect of swelling of the stationary phase with organic solvents on the retention power of the trap is studied. When using pentane or hexane as swelling agent breakthrough volumes of at least 10 ml can easily be obtained for non-polar compounds. For a number of medium polarity compounds breakthrough volumes of 5 ml can be achieved when chloroform is used as the swelling agent. The required drying time is less than 1 minute. Quantitative desorption requires only 75 μl of organic solvent. Solvent elimination prior to transfer to the GC column is carried out using a PTV injector and a multidimensional GC system. The system is applied for the analyses of river water, urine, and serum samples.
    Additional Material: 6 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 16 (1993), S. 459-463 
    ISSN: 0935-6304
    Keywords: LC-GC ; Aqueous samples ; Large volume injection ; PTV injector ; Solid-phase extraction ; Thermal desorption ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A system is described that allows the introduction of large volumes of water samples in capillary GC. Water elimination is carried out in the solvent split mode in a PTV injector with a packed liner. Two ways of separating water and analytes, i.e. evaporative and non-evaporative (solid-phase extraction), are compared. Sampling in the solid-phase extraction mode is favorable both in terms of recovery as well as with regard to sampling time. Quantitative recovery is obtained for priority pollutants ranging in volatility from dimethyl-phenol to phenanthrene. Losses occur for more volatile compounds, but even for these compounds the repeatability of the recoveries remains acceptable. With the system described here, water samples up to at least 1 ml of water can be directly analyzed. The detection limits are in the sub-ppb range.
    Additional Material: 4 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 18 (1995), S. 19-27 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Large volume injection ; PTV injectors ; PTV splitless injection ; PTV solvent split injection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Temperature programmable injectors with liner diameters ranging from 1 to 3.5 mm are evaluated and compared for solvent split injection of large volumes in capillary gas chromatography. The liner dimensions determine whether a large sample volume can be introduced rapidly or has to be introduced in a speed controlled manner. The effect of the injection technique used on the recovery of n-alkanes is evaluated. Furthermore the influence of the liner diameter on the occurrence of thermal degradation during splitless transfer to the analytical column is studied. Guidelines are given for the selection of the PTV liner internal diameter best suited for specific applications.
    Additional Material: 9 Ill.
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  • 6
    ISSN: 0935-6304
    Keywords: Natural gas analysis ; Sulfur components ; Sulfur selective detection ; Universal detectors ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the present contribution, the performance of a number of commercially available selective and universal detectors that can be used in the analysis of sulfur components in natural gas is evaluated in terms of sensitivity, selectivity, reproducibility, quenching effect, stability, and compound dependence of the sulfur response. Investigated detectors include the sulfur chemiluminescnce, the flame photometric, the electron capture, the mass spectrometric, the thermal conductivity, and the flame ionization detector. The sulfur chemiluminescence detector was found to have the best overall performance, e.g., low picogram amounts of sulfur can be detected accurately and the linear dynamic range is more than five orders of magnitude. After careful optimization, the sulfur response of this detector was found to be almost compound independent. All other detectors, including the flame photometric and the electron capture detector, have more or less compound dependent responses.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0935-6304
    Keywords: gas chromatography ; sorptive preconcentration ; air sampling ; VOCs ; nitro-PAH's ; PAHs ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---This paper is concerned with the determination of volatile and semi-volatile organic components in air and gaseous (headspace) samples, focusing primarily on polar analytes. Samples were analyzed by preconcentration on different (ad)sorbents followed by thermal desorption and analysis by capillary gas chromatography. The performance of a cartridge filled with 100% polydimethylsiloxane (PDMS) particles was compared to that of adsorbents like Tenax TA and Carbotrap 300. Though the PDMS phase is non-polar it showed adequate retention for both polar and non-polar components. The blank runs of the PDMS trap were significantly better than those of most adsorbents and did not deteriorate, as was the case with all the conventional adsorbents investigated. With respect to trapping efficiencies, the PDMS phase performed better for most of the analytes under investigation compared to the adsorbents. For a range of analytes including triethylamine, butanone, diacetyl, nicotine, and acetic acid the PDMS phase performed exceptionally well whereas all adsorbents showed unsatisfactory performance. The packed PDMS traps were employed for the determination of organic acids, PAH's and nitro-PAH's in air and for the analysis of the headspace of cacao and hop.
    Additional Material: 9 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 385-393 
    ISSN: 0935-6304
    Keywords: Sorptive preconcentration ; Thermal desorption ; Air enrichment ; Environmental samples ; Natural gas ; PAHs ; Nitro-PAHs ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new method for the preconcentration of trace components from gaseous samples is described. The system is based on enrichment of the solutes on a packed bed of 100% polydimethylsiloxane (PDMS) particles followed by thermal desorption and GC analysis. It was demonstrated that breakthrough volumes for packed PDMS traps can be calculated from theoretical equations. The PDMS material exhibits excellent thermal stability even after 200 consecutive runs. Additional advantages of packed sorbent beds over conventional adsorbent materials include high inertness, the absence of displacement effects and a reduced affinity for water. The practicality of the system was demonstrated by the analysis of air and natural gas using the system described here, components in the range of octane to benso[a] pyrene could be quantitatively trapped and thermally desorbed at mild temperatures. With the present set-up the detection limit is in the order of 0.1 ng/m3 (MSD detector).
    Additional Material: 12 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 18 (1995), S. 124-128 
    ISSN: 0935-6304
    Keywords: Large volume injection ; PTV injector ; PTV solvent split injection ; Packed inserts ; Thermal degradation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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