Detection of conjugated 11-nor-Δ9-tetrahydrocannabinol-9- carboxylic acid in oral fluid

Abstract

The presence of the conjugated marijuana metabolite 11-nor- Δ9-tetrahydrocannabinol-9-carboxylic acid (THCA) glucuronide in oral fluid specimens is described for the first time. Oral fluid specimens were collected using a Quantisal™ device and analyzed for the presence of THCA using two-dimensional gas chromatography with mass spectrometric (GC-MS) detection both before and after hydrolysis. The nature of the conjugation was determined by analyzing specimens from a marijuana user without hydrolysis, with base hydrolysis, with β-glucuronidase treatment, and hydrolysis using sulfatase only. Treatment with sodium hydroxide proved to be the most efficient hydrolytic procedure. Specimens collected over 48 h showed an average conjugation of over 64.5%. The specimens were also analyzed for the active component, tetrahydrocannabinol (THC), which was detected in the oral fluid, in most cases, for up to 24 h. Parent THC was not found to be glucuronide bound. Specimens were then subjected to commercially available immunoassays in order to determine their utility as screening procedures. The metabolite, THCA, was detected in all samples up to and including the specimen 48 h after smoking, using the more sensitive screening assay and twodimensional GC-MS. Moreover, proof that the THCA is conjugated in oral fluid minimizes concerns associated with passive inhalation.