Development of a micropulverized extraction method for rapid toxicological analysis of methamphetamine in hair

We developed a rapid sample preparation method for the toxicological analysis of methamphetamine and amphetamine (the major metabolite of methamphetamine) in human hair by high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS), to facilitate fast screening and quantitation. Two milligrams of hair were mechanically micropulverized for 5 min in a 2-ml plastic tube together with 100 μl of an aqueous solvent containing 10% acetonitrile, 100 mM trifluoroacetic acid and the corresponding deuterium analogues as internal standards. The pulverizing highly disintegrated the hair components, simultaneously allowing the extraction of any drugs present in the hair. After filtering the suspension with a membrane-filter unit, the clear filtrate was directly analyzed by HPLC–MS/MS. No evaporation processes were required for sample preparation. Method optimization and validation study were carried out using real-case specimens and fortified samples in which the drugs had been artificially absorbed, respectively. Concentration ranges for quantitation were 0.040–125 and 0.040–25 ng/mg for methamphetamine and amphetamine, respectively. Real-case specimens were analyzed by the method presented here and by conventional ones to verify the applicability of our method to real-world analysis. Our method took less than 30 min for a set of chromatograms to be obtained from a washed hair sample.