ASPECTS OF THE ELUTION ORDER INVERSION BY PRESSURE CHANGES IN PROGRAMMED-TEMPERATURE GAS-CHROMATOGRAPHY

The phenomenon of elution order inversion in programmed-temperature ga s chromatography, as a result of only changing the head pressure of th e column while retaining the same temperature program, is known to be experimentally detectable. In this paper we analyze some theoretical a spects of this phenomenon. These aspects concern the dependence of the separation on the pressure program for st couple of analytes presenti ng a retention reversal in isothermal gas chromatography (GC). In the theoretical context, the reason why the pressure program will not have a uniform effect on the separation of all crossing-over couples from a mixture, and why it is not possible to obtain a simple correlation f or the separation of a given couple under different pressure condition s is visualized. A complete simulation of the process is required to e valuate the effect of the chosen head pressure-temperature program on the separation of the solutes. (C) 1997 Elsevier Science B.V.