SENSITIVE ASSAY FOR COCAINE AND BENZOYLECGONINE USING SOLID-PHASE EXTRACTION AND GAS-CHROMATOGRAPHY

An improved method for the simultaneous determination of cocaine and benzoylecgonine by means of gas chromatography with nitrogen-phosphorus detection is described. Following a solid-phase extraction and derivatization of benzoylecgonine to its butyl ester, chromatography was performed using a capillary column. The n-propylester of benzoylecgonine served as the internal standard. The assay was linear from 4 to 2000 ng/ml for both cocaine and benzoylecgonine, with a good precision over this concentration range. This method may be particularly useful for small volume samples since it requires only 250 mu l of plasma for analysis of both cocaine and benzoylecgonine.