Background: To facilitate the monitoring of drug abuse by patients, a method was developed and validated for the analysis of amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine, methylenedioxyamphetamine, methylenedioxyethylamphetamine, methylphenidate, cocaine, benzoylecgonine, morphine, codeine, heroin, 6-monoacteylmorphine, methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), delta-9-tetrahydrocannabinol (THC), nicotine, and cotinine in human hair.
Methods: The hair preparation method contains a 3-step wash procedure with dichloromethane followed by a simultaneous hair pulverization and extraction procedure with disposable metal balls. The developed liquid chromatography tandem mass spectrometry method uses a single injection to detect and confirm all 17 abused drugs, including THC, within 4.8 minutes.
Results: Nicotine was validated with a linear range of 800-25,000 pg/mg hair, and all other substances were validated with a linear range of 30.0-2500 pg/mg hair. For inaccuracy and imprecision, the overall bias did not exceed -8.2% and the overall coefficient of variation did not exceed 17.7%. Autosampler stability was proven for 48 hours at 10°C for all substances. Analytical cutoff concentrations were defined for each substance at the lowest validated inaccuracy and imprecision concentration with a bias and coefficient of variation within 15% and qualifier/quantifier ratios within 20% of the set ratio. The analytical cutoff concentrations were 200 pg/mg for codeine and 80.0 pg/mg for 6-MAM, heroin, EDDP, and THC. The analytical cutoff concentration for nicotine was 800 pg/mg and for all other validated substances 30.0 pg/mg. This method was successfully applied to analyze hair samples from patients who were monitored for drug abuse. Hair samples of 47 subjects (segmented into 129 samples) showed 3,4-methylenedioxymethamphetamine, methylphenidate, cocaine, benzoylecgonine, codeine, methadone, EDDP, THC, nicotine, and cotinine above the analytical cutoff.
Conclusions: The method was fully validated, including the validation of the qualifier/quantifier ratios. The analysis of real hair samples proved the efficacy of the developed method for monitoring drug abuse. The results obtained by this method provide the physician or health-care professional with extensive information about actual drug abuse or relapse and can be used for patient-specific therapy.