SCREENING AND IDENTIFICATION OF DRUGS IN HUMAN HAIR BY HIGHPERFORMANCE LIQUID-CHROMATOGRAPHY PHOTODIODE-ARRAY UV DETECTION AND GAS-CHROMATOGRAPHY MASS-SPECTROMETRY AFTER SOLID-PHASE EXTRACTION - A POWERFUL TOOL IN FORENSIC MEDICINE

A method is described to screen for a wide rang of pharmaceuticals in human hair. 75 mg of powdered hair are incubated oe (12 h at 56 degree s C) in 2 ml of distilled water (acidic compounds) or 0.1 M hydrochlor ic acid (neutral and basic compounds). A twin solid-phase extraction o n C-18 cartridges is used for the sample clean-up procedure. Acidic dr ugs are fixed at pH 2 and eluted with 1% ammoniacal methanol while neu tral and basic drugs are retained on the column at pH 8.6 and eluted w ith methanol containing 0.5% acetic acid. The internal standard (I.S.) for the acidic extraction was bupivacaine while the I.S. for the basi c extraction was prazepam. The separation of the drugs was performed u sing both the liquid and the gas chromatographic techniques whereas id entification was achieved using photodiode array and mass spectrometri c detection, respectively. The liquid chromatographic system gives an elution of the drugs following a multi step gradient from a Symmetry C , (Waters) 5 mu m column (250x4.6 mm I.D.) at +30 degrees C with aceto nitrile-phosphate buffer (pH 3.8). Identification is achieved using th e reference data (retention times and spectra) of 675 pharmaceuticals, toxicants and drugs of abuse stored in a personal library. The presen t method has been applied during 6 months in our laboratory. By establ ishing a victim's drug use history, it is a very powerful tool in fore nsic medicine. We illustrate the method with some real cases of police crime investigation.