Separation of nonionic compounds by CE using a lauryl poly(oxyethylene) sulfate additive

A nonionic surfactant (Brij-30) was treated with chlorosulfonic acid to form C12H25(OCH2CH2)(4)OSO3-Na+. Addition of a low concentration of this material to an aqueous solution-acetonitrile electrolyte makes it possible to separate nonionic organic compounds by capillary electrophoresis. Separation is based on differences in the stabilities of analyte-additive complexes in solution. Migration times of analytes can be varied over an unusually large range by varying the additive concentration and the proportion of acetonitrile in the electrolyte. This greatly expands the scope of neutral organic compounds that can be separated by CE. Several examples are given. Some very difficult separations were achieved, such as the baseline resolution of four methylbenz[a]anthracene isomers and the separation of normal and deuterated acetophenone.