Analysis of basic drugs by high-performance liquid chromatography using on-line solid-phase extraction and an unmodified silica column

Abstract

A method is described for the high-performance liquid chromatographic analysis of a number of basic drugs on unmodified silica gel, which employs an aqueous methanol-rich eluent of pH 8. The analytical system was coupled to a column-switching assembly in order to facilitate on-line solid-phase extraction of the drugs from plasma. The method is reproducible, with a coefficient of variation of 3% or less for most compounds, even without internal standardisation. Drug recovery from plasma is efficient, being in excess of 90% in most instances. The drugs were detected by UV absorption at 254 nm.