Detection of THCCOOH in hair by MSD-NCI after HPLC clean-up

Regular consumption of cannabis can easily be detected by examination of ha ir for tetrahydrocannabinol, cannabinol, and cannabidiol. Although several studies have demonstrated that after contamination with smoke or treatment with THC containing shampoos THC is not detectable, or only in small traces , the detection of 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (THCCOOH) should be offered to prove the consumption and metabolisation of THC. Up t o now this confirmation was only available using tandem MS techniques combi ned with negative chemical ionisation, A new method using a normal quadrupo le GC/MS is described. The lack of expensive instruments has to be paid for by a costly and time consuming extraction and clean-up. After the sample h as been digested by 2 M NaOH at 95 degrees C and the neutralised liquid has been extracted with a mixture of n-hexane and ethyl acetate the dried resi due is reconstituted in acetonitrile-methanol-0.01 M sulfuric acid (49:21:3 0, v/v/v) and the cannabinoids separated by HPLC. Each fraction is collecte d over 1 min. Another extraction with n-hexane-ethyl acetate is followed by evaporation, derivatisation, and GC/MS determination, The calibration with THCCOOH spiked hair led to a LOD of 0.3 pg/mg and a LOQ of 1.1 pg/mg. (C) 2000 Elsevier Science ireland Ltd. All rights reserved.