Simultaneous quantitation of cocaine, opiates, and their metabolites in human hair by positive ion chemical ionization gas chromatography mass spectrometry

A sensitive method is developed for the combined extraction of cocaine (COC), cocaethylene (CE), benzoylecgonine (BE), ecgonine methyl ester (EME), norcocaine (NORCOC), 6-acetylmorphine (6-MAM), codeine (COD), norcodeine (NORCOD), morphine (MOR), and normorphine (NORMOR) from human head hair using an enzyme-based digestion technique (Protease VIII/DTT/Tris-buffer pH 6.5 at 22°C). After pH adjustment to 5.5, the digests are extracted with a solid-phase extraction procedure using Bond-Elut Certify columns. The extract residues are evaporated at 40°C, reconstituted in 20 μl of ethyl acetate, and derivatized with the reagents N-methyl-N-trimethylsilylheptafluorobutyramide (MSHFBA), N-methyl-bis-heptafluorobutyramide (MBHFBA), and N-trimethylsilylimidazole (TMSIM). Analyses are performed by positive ion chemical ionization gas chromatography-mass spectrometry using a DB-1 capillary column. Two injections are performed on each extract to optimize sensitivity for all analytes. The assay is capable of reliably quantitating 500 pg/mg of all compounds and is linear to 50 ng/mg, except for BE, which is linear to 25.0 ng/mg. The method was used to analyze human hair samples obtained from cocaine and heroin users. COC, BE, and EME are detectable in all samples, whereas NORCOC, CE, COD, 6-MAM, and MOR are detected in only some samples. Norcodeine and normorphine are not detected. The assay is currently being used to analyze hair samples from a study investigating the mechanisms of drug disposition in hair.