Quantitative determination of cocaine and its metabolites benzoylecgonine and ecgonine by gas-liquid chromatography.

A sensitive and reliable method was developed to determine quantitatively cocaine and its metabolites benzoylecgonine and ecgonine. The method involved the formation of fluoro derivatives which were separated on 3% and 5% OV-1 columns and detected in picomole quantities using an electron capture detector. Ecgonine and benzoylecgonine were derivatized with a mixture of hexafluoroisopropanol-heptafluorobutyric anhydride (1:2). Cocaine was first reduced by LiAlH4 and then acylated by pentafluoropropionic anhydride. Benzoylecgonine, but not ecgonine, could also be determined by reduction and subsequent acylation. This provided the basis for the determination of cocaine, benzoylecgonine and ecgonine from the same sample. Cocaine could be determined in urine and plasma by this method.