Band broadening extracolumn sources

Efficiency, N The column efficiency characterizes the combined effects of the sources of band broadening due to axial dispersion and mass transfer resistance. It is derived from the width of the elution peak observed as the response to the injection of a small, narrow pulse of a dilute solution of a compoimd. It is difficult to correct for the contribution of the extracolumn sources of band broadening which have to be kept small. In preparative and nonlinear chromatography, there is a correlation between the colmnn efficiency and both the steepness of the shock layer and the duration of the band beyond the retention time However, the column efficiency is essentially a concept of linear chromatography, and it is difficult to extend to and use in nonlinear chromatography, except through the shock layer thickness concept. 

Conventional GC instruments are inadequate. When short capillary columns are used at high flowrates, the effects of extracolumn sources of band broadening are amplified, and injection plug width, detection method, and data-processing techniques may contribute to large reductions in system resolving power. 

INSTRUMENTAL REQUIREMENTS FOR HSGC 5.7.1 Sources of Extracolumn Band Broadening... 

In addition to the solute band broadening that occurs on the column, band broadening occurs from other processes. Major sources of extracolumn band... 

Open-cell, flame-based detectors typically have response times of a few milliseconds or less if the capillary separation column is passed through the burner tip and positioned just below the base of the flame. Thus, At is small, and from the detector usually is negligible relative to other extracolumn sources of band broadening. While many HSGC studies have used the FID, few data are... 

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