Peak shape distortions during capillary electrophoretic separations of multicomponent samples in two co-ion buffers

During the capillary electrophoretic separation of a five-component quaternary ammonium analyte sample in two co-ion background electrolytes prepared from phosphoric acid, lithium hydroxide and tetrabutylammonium hydroxide, grossly distorted analyte peaks were observed. The electropherograms were successfully simulated using an earlier mathematical model of electrophoresis that was extended to handle up to eight nonproteic sample ions and two nonproteic background electrolyte co-ions. Peak shape distortion closely followed the predictions made during the recently described simulations of single analyte-two co-ion background electrolyte systems. Peak shape distortion was shown to depend on the relative mobilities of the particular analyte, the non-comigrating system peak and the governing co-ion. Severe peak shape distortion could occur in every multiple co-ion background electrolyte, such as in the indirect detection background electrolytes and charged interacting agent-containing background electrolytes, when certain analyte peaks and the non-comigrating system peaks overlap. (C) 1997 Elsevier Science B.V.