Automated headspace solid-phase dynamic extraction for the determination of cannabinoids in hair samples Frank Musshoff * , Dirk W. Lachenmeier, Lars Kroener, Burkhard Madea Institute of Legal Medicine, University of Bonn, Stiftsplatz 12, D-53111 Bonn, Germany Received 26 August 2002; received in revised form 19 November 2002; accepted 5 January 2003 Abstract This article describes a fully automated procedure for detecting cannabinoids in human hair samples. The procedure uses alkaline hydrolysis and headspace solid-phase dynamic extraction (HS-SPDE), followed by on-coating derivatization and gas chromatography–mass spectrometry (GC–MS). SPDE is a further development of solid-phase microextraction (SPME), based on an inside needle capillary absorption trap. It uses a hollow needle with an internal coating of polydimethylsiloxane as extraction and pre-concentration medium. Ten mg of hair were washed with deionised water, petroleum ether and dichloromethane. After adding deuterated internal standards, the sample was hydrolyzed with sodium hydroxide and directly submitted to HS-SPDE. After absorption of analytes for an on-coating derivatization procedure, the SPDE-needle was directly placed into the headspace of a second vial containing N-methyl-N-trimethylsilyl-trifluoroacetamide before GC–MS analysis. The limit of detection was 0.14 ng/mg for D 9 -tetra- hydrocannabinol, 0.09 ng/mg for cannabidiol, and 0.12 ng/mg for cannabinol. Absolute recoveries were in the range of 0.6 to 8.4%. Linearity was verified over a range from 0.2 to 20 ng/mg, with coefficients of correlation between 0.998 and 0.999. Intra- and inter-day precision were determined at two different concentrations and resulted in ranges between 2.3 and 6.0% (intra-day) and 3.3 and 7.6% (inter-day). Compared with conventional methods of hair analysis, this automated HS-SPDE–GC–MS procedure is substantially faster. It is easy to perform without using solvents and with minimal sample quantities, and it yields the same sensitivity and reproducibility. Compared to SPME, we found a higher extraction rate, coupled with a faster automated operation and greater stability of the device. # 2003 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Cannabinoids; Hair analysis; SPDE; SPME 1. Introduction Hair analysis has proved to be a reliable tool for the retrospective detection of chronic drug abuse in clinical and forensic toxicology [1,2]. Gas chromatography–mass spec- trometry (GC–MS) using selected-ion monitoring (SIM) seems to be the method of choice for determining the presence of cannabinoids in hair samples [3–9]. Enhanced sensitivity was achieved by using the negative ion chemical ionization (NCI) mode [10–13] or tandem mass spectro- metry (MS–MS) [14–18]. Besides the parent drug D 9 -tetrahydrocannabinol (THC), the cannabis constituents cannabinol (CBN) and cannabidiol (CBD) are regularly found in hair samples [6]. In our experience, the main THC metabolite 11-nor-D 9 -tetrahydro- cannabinol-9-carboxylic acid (THC–COOH) was seldom identified, even in THC positive cases. For a quantitative determination of THC–COOH in the lower pg/mg range, MS–MS technique is recommended. Headspace solid-phase microextraction (HS-SPME) is a sampling technique that allows an extraction from small amounts of biological material. HS-SPME is based on the partitioning of analytes between the sample, the headspace above the sample, and a coated fused-silica fiber [19,20]. THC, CBD and CBN have been analyzed so far by means of SPME using the direct extraction technique from an aqueous Forensic Science International 133 (2003) 32–38 * Corresponding author. Tel.: þ49-228-738316; fax: þ49-228-738368. E-mail address: f.musshoff@uni-bonn.de (F. Musshoff). 0379-0738/03/$ – see front matter # 2003 Elsevier Science Ireland Ltd. All rights reserved. doi:10.1016/S0379-0738(03)00047-1