An evaluation of the cut-off value of methamphetamine in hair samples via HPLC-MS/MS.

Methamphetamine (MAMP) is one of the most commonly abused illicit drugs in Asian countries, which belongs to the amphetamine-type stimulant class of substances. To detect the chronic drug misuse, human hairs have often been used as analytical specimens due to their long detection windows and easy accessibility. However, there is no investigation regarding the cut-off value of MAMP detection used in black-hair Chinese populations. Based on the analytical data obtained from 563 MAMP users, the cut-off value was found to be 0.97 ng/mg for the simultaneous detection of MAMP and amphetamine (AMP) ≥0.004 ng/mg (LOD). Through the established HPLC-MS/MS analytical method, the limits of detection and quantification of MAMP were 0.004 and 0.01 ng/mg, respectively. The cut-off value was optimized by AMP detection rate and receiver operating characteristic analysis, and the results were consistent with the previously reported MAMP/AMP ratio.