Application of a simple and sensitive GC-MS method for determination of morphine in the hair of opium abusers.

Thirty hair samples were collected from male opioid abusers for whom the presence of morphine in their urine samples was confirmed by thin layer chromatography (TLC). The hair samples were decontaminated by washing with isopropanol, deionized water, and isopropanol, dried at room temperature, and cut into small pieces. Samples of the latter (30 mg ) were digested by incubation in a mixture of methanol-trifluoroacetic acid (9:1) for 18 h at 45 degrees C and sonicated to improve the extraction process. The methanolic phase was evaporated to dryness under a stream of nitrogen at 50 degrees C. The sample was derivatized by addition of N-methyl- N-trimethylsilyltrifluoroacetamide (MSTFA) and 1% trimethyliodosilane (TMIS) at 70 degrees C for 20 min, with sonication. Derivatized samples (1 microL) were injected into a gas chromatograph-mass spectrometer (GC-MS) system fitted with a capillary column; the Finnigan MS was operated in SIM mode. Naltrexone was used as internal standard (IS). The masses of the ions selected for morphine and naltrexone were 429 and 557, respectively. The limit of quantitation was set at 0.03 ng mg(-1) hair. By using the above procedure we detected morphine in all the samples examined, in the concentration range 0.26-10.31 ng mg(-1 )hair.