High-performance liquid chromatographic determination of cocaine and benzoylecgonine by direct injection of human blood plasma sample into an alkyl-diol-silica (ADS) precolumn.

A column-switching high-performance liquid chromatographic method with UV detection for the determination of cocaine (COC) and benzoylecgonine (BZE) in human blood plasma samples is described. The method uses an alkyl-diol-silica ADS-C18 extraction precolumn. A 50- micro L plasma sample was introduced to the ADS precolumn in order to separate the analytes from proteins and endogenous compounds.