Use of headspace solid-phase microextraction (HS-SPME) in hair analysis for organic compounds

Headspace solid phase microextraction (HS-SPME) has advantages of high puri ty of the extract, avoidance of organic solvents and simple technical manip ulation and can be used in combination with gas chromatography-mass spectro metry (GC-MS) in the hair analysis of a number of drugs. HS-SPME coupled wi th the hydrolysis of the hair matrix by 4% sodium hydroxide in the presence of excess sodium sulphate and of a suitable internal standard proved to be a convenient one-step method for the measurement of many lipophilic basic drugs such as nicotine, amphetamine derivatives, local anaesthetics, phency clidine, ketamine, methadone, diphenhydramine, tramadol, tricyclic antidepr essants and phenothiazines. Detection limits were between 0.05 and 1.0 ng/m g. From spiked IO-mg hair samples absolute recoveries between 0.04 and 5.7% were found. These recoveries decreased considerably if larger sample amoun ts were used, perhaps due to increased drug solubility in the aqueous phase or to elevated viscosity in the presence of dissolved hair proteins. Becau se of the phenolic hydroxyl group a change of pH after alkaline hair digest ion (by adding excess orthophosphoric acid) was necessary for the detection of ag-tetrahydrocannabinol (Delta(9)-THC), cannabinol (CBN) and cannabidio l (CBD) by HS-SPME. Nevertheless, the detection limits were such that only CBN could be detected in hair of a consumer. Clomethiazole, a compound hydr olysed in alkali, was measured by HS-SPME after extraction with aqueous buf fer. The detection limit was 0.5 ng/mg. Cocaine could not be detected by HS -SPME. The application of HS-SPME to hair samples from several forensic and clinical cases is described. (C) 2000 Elsevier Science ireland Ltd. All ri ghts reserved.