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  • 1
    Electronic Resource
    Electronic Resource
    Possibilities and limitations of steam distillation-extraction as a pre-concentration technique for trace analysis of organics by capillary gas chromatography
    Amsterdam : Elsevier
    Journal of Chromatography A 279 (1983), S. 395-407 
    Details
    ISSN: 0021-9673
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0021-9673(01)93639-8
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Possibilities and limitations of dynamic headspace sampling as a pre-concentration technique for trace analysis of organics by capillary gas chromatography
    Amsterdam : Elsevier
    Journal of Chromatography A 289 (1984), S. 171-182 
    Details
    ISSN: 0021-9673
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0021-9673(00)95086-6
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Gas chromatographic method for simulated distillation up to a boiling point of 750°C using temperature-programmed injection and high temperature fused silica wide-bore columns (1989)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 12 (1989), S. 16-22 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Wide bore capillary columns ; Temperature programmed injection ; Simulated distillation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is demonstrated that linear injection characteristics are obtained for a wide boiling point range sample using a temperature-programmed injector in combination with wide-bore fused silica columns. The applicability of the described combination for high temperature simulated distillation is described. The method, using external standardization, gives accurate and repeatable results for different types of samples in the boiling range between 50 and 750°C. The lifetime of the fused silica wide-bore columns was found to be acceptable, viz. over 80 temperature-programmed cycles between ambient and 430°C. Some comments are made on the accuracy of boiling points for normal alkanes.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240120106
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  • 4
    Electronic Resource
    Electronic Resource
    Temperature programmed retention indices: Calculation from isothermal data. Part 1: Theory (1985)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 8 (1985), S. 607-610 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography, GC ; Temperature programmed retention indices ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Direct conversion of isothermal to temperature programmed indices is not possible. In this work it is shown that linear temperature programmed retention indices can only be calculated from isothermal retention data if the temperature dependence of both the distribution coefficients and the column dead time are taken into account.Procedures are described which allow calculation of retention temperatures and from these, accurate programmed retention indices. Within certain limits the initial oven temperature and programming rate can be chosen freely. The prerequisite for this calculation is the availability of reliable isothermal retention data (retention times, retention factors, relative retention times, or retention indices) at two different temperatures for one column.The use of compiled isothermal retention indices at two different temperatures for the calculation of retention temperatures and thus temperature programmed indices is demonstrated. For the column for which programmed retention indices have to be determined, the isothermal retention times of the n-alkanes and the column dead time as a function of temperature have to be known in addition to the compiled data for a given stationary phase.Once the programmed retention indices have been calculated for a given column the concept allows the calculation of temperature programmed indices for columns with different specifications. The characteristics which can be varied are: column length, column inner diameter, phase-ratio, initial oven temperature, and programming rate.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240080926
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  • 5
    Electronic Resource
    Electronic Resource
    Temperature programmed retention indices: Calculation from isothermal data. Part 2: Results with nonpolar columns (1985)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 8 (1985), S. 611-617 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography, GC ; Temperature programmed retention indices ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The procedure for calculating linear temperature programmed indices as described in part 1 has been evaluated using five different nonpolar columns, with OV-1 as the stationary phase. For fourty-three different solutes covering five different classes of components, including n-alkanes and alkyl-aromatic compounds, both isothermal and temperature programmed indices were determined. The isothermal information was used to calculate temperature programmed indices. For several linear programmed conditions accuracies better than 0.51T-units were usually obtained. The results are compared with published procedures.It is demonstrated that isothermal retention information obtained on one column can be transferred to another column with the same stationary phase but different column dimensions and/or phase ratio. The temperature programmed indices calculated in this way also have an accuracy better than 0.51T-u.The temperature accuracy and precision of the GC-instrumentation used was of the order of 0.1°C. All calculations can be run with a Basic-programmed microcomputer.
    Additional Material: 12 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240080927
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  • 6
    Electronic Resource
    Electronic Resource
    Increased speed of steroid analysis by capillary GC and GC-MS; effects of sample pretreatment and sample introdution (1984)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 7 (1984), S. 414-422 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary columns ; Steroid analysis ; Sample pretreatment ; Sample introduction ; Separation speed ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quantitative analysis of steroids and their metabolites in urine samples calls for increased speed of sample clean-up, of the derivatization procedure, and of separation. A fast procedure for sample pretreatment, which can be performed within 8 hours, is introduced and evaluated. It is shown that use of fast pretreatment in combination with narrow bore columns, which are compatible with existing instrumentation, can considerably increase, laboratory throughput. The effect of different sample introduction techniques (e.g. splitless, on-column, and moving needle) on column efficiency and resolution is demonstrated and discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240070713
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  • 7
    Electronic Resource
    Electronic Resource
    The effect of column characteristics on the minimum analyte concentration and the minimum detectable amount in capillary gas chromatographyBased on a lecture delivered at the First Latin-American Congress on Chromatography (COLACRO) Rio de Janeiro, Brazil, March 17-19, 1986. (1986)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 9 (1986), S. 752-759 
    Details
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Detection limits ; Trace analysis ; Narrow bore columns ; Wide bore columns ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The need for faster and more efficient separations of complex mixtures of organic compounds by gas chromatography has led to the development of small inner diameter open tubular columns. Owing to their decreased plate height, extremely narrow peaks are obtained. When differently sized columns with equal plate numbers are compared, injection of a fixed amount of a solute will give the highest detector signals for the smallest bore columns. When P is defined as the ratio of the column inlet and outlet pressures, it can be seen from theory that under normalized chromatographic conditions the minimum detectable amount (Qº) for a mass flow sensitive detector increases proportionally to the square of the column diameter for P = 1. In the situation of greater interest in the practice of open tubular gas chromatography where P is large, a linear relationship is derived between Qº and the column diameter.It is a widespread misunderstanding, however, that narrow bore capillary columns should be used for this reason in trace analysis. If a fixed relative contribution of the injection band width to the overall peak variance is allowed, a decreased plate height drastically restricts the maximum sample volume to be injected. It is shown that the minimum analyte concentration in the injected sample (Cº) is inversely proportional to the column inner diameter when a mass flow sensitive detector is used. For actual concentrations less than Cº, sample preconcentration is required. The effect of peak resolution and selectivity of the stationary phase in relation to Cº and Qº will be discussed as well. The validity of the given theory is experimentally investigated. Minimum analyte concentrations and minimum detectable amounts are compared using columns with different inner diameter.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240091208
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