Interlaboratory comparison of quantitative determination of amphetamine and related compounds in hair samples

Testing human hair for drugs of abuse is a relatively new technique which requires control before being fully accepted in justice applications. Laboratories must be able to demonstrate that they can accurately determine what drugs are present in unknown hair samples and at what levels. To date few exercises have been organized in USA, Germany and France, all devoted to opiates, cocaine and cannabis. However, the number of drugs which can be detected in hair is growing every day. Among them, amphetamine and related compounds, such as MDMA, are of major interest due to increasing abuse. At the initial state of this work, four different preparation procedures were used to test amphetamine, MDA and MDMA. Direct methanol extraction, acid (HCl 0.1 N), alkaline (NaOH 1 N) and enzymatic (beta-glucuronidase/arylsulfatase) hydrolyses were compared. Best recoveries were observed after alkaline hydrolysis. The same hair sample was powdered and sent to 16 laboratories, in USA (4), Germany (6), France (3), Spain (1), Japan (1) and Korea (1) to test amphetamine, methamphetamine, MDA and MDMA. All laboratories returned results within 3 months. Amphetamine tested positive 13 times with concentrations ranging from 3.3 to 17.5 ng/mg. Only 2 laboratories identified methamphetamine, using GC/MS, at low concentration (0.8 and 1.8 ng/mg), which appears to be a false positive. MDA and MDMA both tested positive in 14 cases, with concentrations ranging from 1.8 to 19.5, and 8.9 to 100.0 ng/mg for MDA and MDMA, respectively. These scattered results clearly indicated that new exercises are needed to ensure quality in hair testing. This is one of the major aims of the Society of Hair Testing.