Pressurized solvent extraction for the determination of illicit drugs in hair by HPLC-MS/MS

Plasma and urine are the most commonly used matrices for illicit drug testing, but since 1979 there has been an increasing interest in the development of analytical methods in alternative matrices such as hair [1]. Hair has the advantage of a substantially longer detection window (months to years) which enables retrospective investigation of chronic consumption. In addition, hair is a durable and stable matrix difficult to adulteration in which toxic substances are preconcentrated and remain for a long time without significant alterations; furthermore the sampling is not invasive. Indeed hair analysis of illicit drugs has recently been codified in the Italian legislation as a monitoring tool in the field of workplace safety. The critical step is certainly the extraction phase, usually performed by solid liquid extraction for multiclass methods; the main drawback is the long contact time (from 16 to 20 hours) between hair and solvent necessary to have good recoveries. Times are greatly reduced if the extraction is assisted by ultrasonic or increased temperature. Pressurized Liquid Extraction (PLE) was applied to significantly reduce extraction time since there are no PLE applications in this field. So a method based on HPLC-ESI-MS/MS has been developed and validated for multiresidual determination of illicit drugs from hair: amphetamine, methamphetamine, mescaline, MDA, MDMA, MDEA, cocaine, benzoylecgonine, nor-cocaine, ketamine, phencyclidine, diacetylmorphine, morphine, 6-monoacetylmorphine, codeine. PLE led to reduce the analysis time and automate the extraction process, taking into account sample washing to remove external contamination and the clean-up of the extracts. Satisfactory extraction rates have been obtained using water as extracting and 10 minutes as extraction time.