Applications of chemically modified and coated etched capillaries for the separation of basic molecules

A comparison of the migration behavior of two antibiotics is made between s everal types of etched columns used in the open tubular format of capillary electrochromatography. The types of columns evaluated are: 1) etched and u nmodified; 2) etched and bonded with an octadecyl moiety; 3) etched and bon ded with:a cholesterol moiety; 4) etched and coated with an anionic surfact ant; and 5) etched and coated with a neutral (zwitterionic) surfactant. In addition to evaluating the influence of the stationary phase, the effect of buffer pH is also measured. Each of the antibiotic samples consist of seve ral components and the resolution capabilities of the various columns are t ested in order to determine how OTCEC can be optimized for the analysis of small basic compounds.