Hair analysis for drugs of abuse. XVII. Simultaneous detection of PCP, PCHP, and PCPdiol in human hair for confirmation of PCP use.

The paper reports the simultaneous detection hair of phencyclidine (PCP) and its two major metabolites, 1-(1-phenylcyclohexyl)-4-hydroxypiperidine (PCHP) and trans-1-(1-phenyl-4-hydroxycyclohexyl)-4'-hydroxypiperidine (t-PCPdiol) in human hair. The detection of these metabolites provides definitive evidence that a positive hair analysis result is due to active PCP use and not due to external contamination of the hair specimen. Hair (5 mg) from known PCP users was washed three times with 0.1% sodium dodecyl sulfate for 1 min before analysis. Three extraction methods were compared: methanol-5N HCl (20:1) (Method A), 10% HCl (Method B), and 2N sodium hydroxide digestion (Method C). PCP-d5 and PCHP-d5 were used as internal standards. Extracts were purified by Bond Elut Certify solid-phase extraction procedures. Samples were derivatized with N,O-bis-trimethylsilyl acetamide and analyzed by gas chromatography-mass spectrometry. Compared with Method A, the extraction efficiencies of Methods B and C for PCP were 83-89%; however, the extraction efficiencies of Methods B and C for the two metabolites were only half or less than that of Method A. Method A was therefore selected for the analysis of clinical hair specimens from eight PCP users. The coefficients of variation of this method (n = 5) for PCP at 4 ng/mg and for PCHP and t-PCPdiol at 0.2 ng/mg were 2.13, 6.09, and 9.38%, respectively. In the eight hair specimens, PCP values ranged between 0.33 and 14 ng/mg. PCHP between 0.02 and 0.12 ng/mg, and trans-PCPdiol between 0.09 and 0.45 ng/mg. It was found that t-PCPdiol was the major metabolite in the PCP users' hair specimens, although t-PCPdiol was a minor metabolite in the hair specimens of rats intoxicated with PCP.