Retention simulation in gas chromatography

It is demonstrated that the differential equation (Model 1) describing a peak motion in GC process can be served as the general base for retention simulation. The integration equation (Model 2) is a special form of solution of the differential equation only in constant pressure mode. Both models are not analytically solvable in term of retention time, and numerical calculations based on standard algorithms (Ronge-Kutta algorithm for Model I, Simpson algorithm for Model 2) have to be used. Simulation results show the existence of some difference between the models in pressure varying GC conditions. The difference usually varies from 0.01 to 0.15 min or more depending on the solutes, operating pressure and temperature conditions. A q index is proposed to correlate the model difference. (C) 1999 Elsevier Science B.V. All rights reserved.