Published: Journal of Analytical Toxicology, ISSN 0146-4760, Volume 30, Issue 7, September 2006, pp.413-418

Detection of the Marijuana Metabolite 11-Nor-D9- Tetrahydrocannabinol-9-Carboxylic Acid in Oral Fluid Specimens and Its Contribution to Positive Results in Screening Assays
Christine Moore[1], Wayne Ross[2], Cynthia Coulter[1], Laura Adams[2], Sumandeep Rana[1], Michael Vincent[1], and James Soares[1]
[1]Immunalysis Corporation, 829 Towne Center Drive, Pomona, California 91767 and
[2]Redwood Toxicology Laboratory, 3650 Westwind Boulevard, Santa Rosa, California 954037

The detection of the marijuana metabolite 11-nor-D9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) in oral fluid specimens is described, and its contribution to an immunoassay for the detection of cannabinoids is investigated. Oral fluid specimens, screened using an enzyme-linked immunosorbent immunoassay (ELISA), were carried forward to confirmation for both tetrahydrocannabinol (THC) and THC-COOH using gas chromatography–mass spectrometry (GC–MS). One hundred and fifty-three specimens were analyzed, of which 143 screened positive for cannabinoids. Ninety-five (66.4%) of these specimens were positive for both THC and THC-COOH; 14 (9.7%) were positive for THC-COOH only, and 27 (18.8%) were positive for THC only. The GC–MS assay for the detection of THC-COOH in oral fluid was linear to 160 pg/mL with a limit of quantitation of 2 pg/mL. The detection of the marijuana metabolite, THC-COOH, in 76.2% of oral fluid specimens screening positive for cannabinoids is reported. As a potential defense against passive exposure claims, proposed SAMHSA regulations may require the simultaneous collection of a urine sample when oral fluid samples are used. The detection of the metabolite, THC-COOH, is a significant alternative to this approach because its presence in oral fluid minimizes the argument for passive exposure to marijuana in drug testing cases.

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