Gas chromatography instruments

Tipler, A. (1993). Gas chromatography instrumentation, operation, and experimental considerations. In Gas Chromatography A Practical Approach, ed. Baugh, P.J., Oxford University Press, Oxford, pp. 15-70. 

Although changes in temperature, whether of the laboratory or the oven, the injection port of a gas chromatography instrument, or any other con-... 

Figure 3.1 Two-dimensional gas chromatography instrumental configurations (a) direct transfer heart-cut configuration (b) multiple parallel trap configuration (c) multiple parallel column configuration.

Gas Chromatography instrument with detector interface only... 

Apparatus. The automated on-line SFE-gas chromatography instrumentation consisted primarily of four sections which included a high-pressure pump and extraction cell, a switching valve and interface region, a gas chromatograph with a flame ionization detector, and a minicomputer and its associated interface circuitry. A schematic diagram of this instrumentation is shown in Figure 6. 

Figure 6. Schematic diagram of the on-line supercritical fluid extraction-gas chromatography instrumentation. (Reproduced from Ref. 13. Copyright 1987 American Chemical Society.)...

Holland P. M., Mustacich R. V., Everson J. F., Foreman W., Leone M., Sanders A. H., and Naumann W. J., Correlated column micro gas chromatography instrumentation for the vapor detection of contraband drugs in cargo containers, SPIE Proc., 2276, 79-86, 1994. 

Katsanos, N.A. Karaiskakis, G. Measurement of diffusion coefficients hy reversed-flow gas chromatography instrumentation. J. Chromatogr. 1982, 237, 1-14. 

There may be other variations on this simple design. Some instruments have heated ovens in order to maintain the column at a specified temperature, fraction collectors, and microprocessor-controlled data-handling systems. Additional filters for the solvent and sample may also be included. You may find it interesting to compare this schematic diagram with that shown in Technique 22 (Figure 22.2) for a gas-chromatography instrument. Many of the essential components are common to both types of instruments. 

Most modern gas chromatography instruments are equipped with computer-based data stations. Interfacing the instrument with a computer allows the operator to display and manipulate the results in whatever maimer might be desired. The operator thus can view the output in a convenient form. The computer can display the actual gas chromatogram and display the integration results. It can even display the result of two experiments simultaneously, making a comparison of parallel experiments convenient. 

Gas chromatography instrumentation is discussed in Chapter 5 see also Appendix 1. As examples, the following pyrolyser units, produced by CDS Instruments, are available. 

R. ViUalobos and R. Annino, Process Gas Chromatography, Instrument Society of America (1992). 

Despite the many advances in capillary gas chromatography instrumentation and the remarkable resolution achievable, it has proven difficult to standardize a test method for the analysis of a mixture as complex as petroleum naphtha. Because of the proliferation of numerous, similar columns and the endless choices of phase thickness, column internal diameter, length, etc., as well as instrument operating parameters, many laboratories use similar but not identical methods for the capillary GC analysis of petroleum naphthas. Even minute differences in column polarity or column oven temperature, for example, can change resolution or elution order of components and make their identiflcation an individual interpretive process rather than the desirable, objective application of standard retention data. To avoid this, stringent column specifications and temperature and flow conditions have been adopted in this test method to ensure consistent elution order and resolution and reproducible retention times. Strict adherence to the specified conditions is essential to the successful application of this test method. 

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