GC/MS quantitation of benzoylecgonine following liquid-liquid extraction of urine.

An analytical procedure for the determination of benzoylecgonine in urine by GC/MS using a two step liquid-liquid extraction scheme has been developed. Benzoylecgonine is one of the principle metabolites of cocaine. The extraction uses a wash step prior to extraction and derivatization and requires 0.5 mL of urine. Benzoylecgonine is extracted in good % recovery at a basic pH by using 4 mL of dichloromethane. The method is accurate and sensitive and allows the quantitation of benzoylecgonine in urine at or below the National Institute on Drug Abuse confirmation cutoff level of 150 ng/mL.