PREDICTION OF THE ELUTION PROFILES OF HIGH-CONCENTRATION BANDS IN GAS-CHROMATOGRAPHY

The prediction of band profiles in non-linear gas chromatography requires the use of a mass balance equation for the carrier gas and for the components of the feed. An additional equation is required to account for the non-linearity of the pressure profile and the compressibility of the gas phase. Thus, the sorption effect, which is insignificant in liquid chromatography, becomes of major importance in gas chromatography. Originating from the difference between the partial molar volumes of the retained components in the mobile and the stationary phases, this effect combines with the isotherm effect to control the elution profile of high-concentration bands. The influence of the various parameters which determine the relative intensity of the sorption and the isotherm effects is discussed and illustrated.