Analysis of cocaine, benzoylecgonine, and cocaethylene in urine by HPLC with diode array detection

A solid phase extraction method was developed for the isolation of cocaine, benzoylecgonine, and cocaethylene from urine followed by high-performance liquid chromatography/diode array detection. The application of a new solid hybrid phase extraction technology produced much cleaner extracts than conventional extraction procedures and made the selective extraction of substances with different polarities possible. Two internal standards with great structural resemblance to benzoylecgonine (a carboxylic acid) and to the two esters, cocaine and cocaethylene, respectively, were synthesized. A linear response over a broad concentration range was obtained. The sensitivity, specificity, and accuracy were satisfactory for each analyte. Hydrolysis of cocaine and cocaethylene to benzoylecgonine during extraction and analysis was less than 0.5%. The method described can be used to corroborate cocaine use, to establish cocaine overdoses, and to study pharmacological effects of cocaine and its metabolites.