Effect of a soluble ionic polymer on the separation of anions by capillaryelectrophoresis

A silica capillary for CE analysis of anions can be conditioned with NaOH, rinsed with water, coated with a cationic polymer, and equilibrated with th e background electrolyte in only 2 min for each of the four steps. The coat ed surface has a positive charge that gives a substantial anodic electroosm otic flow (EOF) over the range of pH 2.5-12.0. The migration times of sampl e anions and a neutral marker (used for EOF calculations) are generally rep roducible to an RSD of 1% or better, both for successive runs on a single c apillary and from capillary to capillary. It was shown that the type of buf fer used affects the EOF of a coated capillary. A concentration of 100 mM o r higher sodium chloride minimizes differences in EOF with different buffer s and also gives sharper peaks for sample anions. (C) 2001 Elsevier Science B.V. All rights reserved.