Nonaqueous capillary electrophoresis in pharmaceutical analysis.

Nonaqueous media have shown to be useful for CE separations. It is possible to obtain high selectivities of closely related compounds without using any additive in the electrophoresis medium. The physicochemical parameters of some selected solvents and their influence on separation are discussed. Separations of small compounds with equal or almost equal charge-to-mass ratios have been performed in both aqueous- and nonaqueous-based media and compared. Examples of the use of nonaqueous media for drug impurity testing are given, and precautions for obtaining quantitative and reproducible analysis in nonaqueous media are discussed.