Published: Journal of Analytical Toxicology, ISSN 0146-4760, Volume 26, Number 3, April, pp. 270-274

Quantitation of Cocaine and Its Major Metabolites in Human Saliva Using Gas Chromatography–Positive Chemical Ionization-Mass Spectrometry (GC–PCI-MS)
P. Cámpora, A.M. Bermejo, M.J. Tabernero, and P. Fernández
Institute of Legal Medicine, Forensic Toxicology Service, Faculty of Medicine, University of Santiago de Compostela, Spain

An analytical method for the simultaneous determination of cocaine (COC) and its major metabolites, ecgonine methyl ester (EME) and benzoylecgonine (BEG), in saliva was developed. The method involves liquid–liquid extraction in Toxitubes A®, derivatization with 99:1 (v/v) N,O-bis-trimethylsilyltrifluoroacetamide (BSTFA)/trimethylchlorosilane (TMCS) and gas chromatography–mass spectrometry (GC–MS) determination. The detector response thus obtained is linear over the range 25–1000 ng/mL, with a reproducibility better than 93% and a recovery close to 100% for the three analytes. The limits of detection achieved were 0.9 ng/mL for EME, 2.2 ng/mL for cocaine, and 0.2 ng/mL for BEG, and the limits of quantitation were 3.0 ng/mL for EME, 7.4 ng/mL for cocaine, and 0.8 ng/mL for BEG. The proposed method was applied to 48 saliva samples from cocaine users, 96% of which were positive for the drug and/or its metabolites. Saliva is thus a suitable biological fluid for determining cocaine, EME, and BEG by GC–PCI-MS.

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