Investigation of column and instrumental parameters for fast gas chromatography analysis

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Virginia Tech

The objective of this study was to determine the capability and applicability of a conventional gas chromatography system for fast chromatography. Many gas chromatographic separations actually require much Iss time than js actually being spent on the analysis. Capillary columns are known to be very efficient due to the long lengths and thin stationary phase films. However, analysis can be done much faster if shorter column lengths and thinner stationary phases are used because the retention time is a function of the column length and stationary phase film thickness.

This study involves varying a number of column and instrumental parameters in order to determine their effect on the chromatographic analysis time. The parameters which were varied include the column stationary phase film thickness, the column length, the injection volume, the split ratio, the column position, the injector liner, and the flow and temperature programming rates. The effect of column length on the average linear gas velocity was also determined by plotting the Golay equation for each. The Golay equation (12) illustrates the effect of the various column parameters on column efficiency.

The most detrimental effect of decreasing the analysis time is the loss of resolution that may occur. Both shorter lengths and faster than optimum flow rates result in lower resolution. By careful adjustment of some column parameters, the loss in resolution can be minimized.

The results of this research show that many gas chromatographic analyses require much less time than is actually spent and that a fast analysis can be achieved with little to no loss in resolution.

analysis time, resolution, fast GC