CONSEQUENCES OF ION-EXCHANGE AND SORPTION EFFECTS ON PH WAVES PROPAGATING IN A STRONG-BASE ANION-EXCHANGE COLUMN

When pH buffers are used in frontal anion exchange chromatography, it is known that important transient pH variations may occur, even if pi-Is are identical in preequilibration and feed. This effect was earlier studied with the aid of equilibrium theory extended to the case where dissociation reactions are involved. In the present paper, the sodium acetate/acetic acid system has been revisited but accounting for sorption effects. Sorption experiments were performed to determine the ratio between stationary and mobile phases as a function of ionic concentration. Column experiments with respectively alkaline and acid acetate buffers have been performed and modelled (computer program Impact). Sorption effects have been taken into account; a good prediction of pH and acetate breakthrough curves has thus been achieved.