SYSTEM PEAKS IN CAPILLARY-ZONE-ELECTROPHORESIS - WHAT ARE THEY AND WHERE ARE THEY COMING FROM

If zones do not contain any sample ionic species and contain only ioni c species of the background electrolyte (BGE) with a composition, howe ver, different from that of the BGE with regard to the concentrations of these ionic species and/or the pH in the zone, they can migrate wit h a specific mobility through the BGE. Of course, these BGE-like peaks will only be visible in electropherograms if the ionic species of the BGE can be observed by the detector. In this paper we propose to appl y the term system peaks exclusively for BGE-like peaks and a model is given for the calculation of the mobilities of such system peaks. Thes e system peaks can be created by directly introducing BGE-like zones w ith a composition different from the BGE or can be induced by the inje ction of a sample or even water. Several examples of system peaks are given. (C) 1997 Elsevier Science B.V.