Testing for drugs in hair. Critical review of chromatographic procedures since 1992.

Up to now, more than 50 pharmaceuticals or drugs of abuse have been reported to be detectable in hair after oral or parenteral administration. The present paper reviews the literature devoted to drug testing in hair that has been published since 1992. Procedures for the detection of opiates, cocaine, amphetamines and cannabis in hair are described in detail. In particular, the papers on benzodiazepines show an increasing number of procedures using negative chemical ionisation with GC-MS and diode array detection with HPLC in hair analysis. For the most important benzodiazepines, diazepam and flunitrazepam, reliable methods now exist. On the other hand, the problem of the detecting tetrahydrocannabinol metabolites using different techniques is not yet solved. Some progress is observed in the detection of low dose drugs, like fentanyl and its derivatives or LSD. For most of the analyses using chromatographic techniques, the main data on sample preparation and analytical determinations are listed. Some new findings, based on the experience of the authors, are also added.