Modeling counter-current chromatography with non-ideal injection

In general counter-current chromatography systems, there are several off-column fittings between injector and column inlet, such as bends, valves, connecting tubes and joints. Due to these off-column fittings, the sample will diffuse in the mobile phase and form an irregular distribution when it flows from the injector to the column inlet. Thus, the concentration distribution of the solutes at the column inlet is a continuous curve (called the injection profile). As some previous research reveals, it is necessary to input actual injection profile into the simulation model to mimic elution profile. Therefore, we built a non-ideal CCC model whose initial value is from the actual injection profile, and validated the rationality of this model with iteration method. The simulation analysis of different injection profiles shows the conditions whereby a discrete injection profile can replace the actual injection profile in the non-ideal CCC model for accurate simulation elution. Simulation elution under such conditions reveal that non-ideal injection model can reflect the relationship between the injection profile and elution profile, and help to explain the reasons of irregular change in elution profile, like the tailed peak and flat peak.