Detection of Δ9-tetrahydrocannabinolic acid A in human urine and blood serum by LC-MS/MS

✍ Scribed by Julia Jung; Juergen Kempf; Hellmut Mahler; Wolfgang Weinmann

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 380 KB
• Volume: 42
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/jms.1167

✦ Synopsis

Abstract

Δ9‐Tetrahydrocannabinolic acid A (Δ9‐THCA‐A) is the precursor of Δ9‐tetrahydrocannabinol (Δ9‐THC) in hemp plants. During smoking, the non‐psychoactive Δ9‐THCA‐A is converted to Δ9‐THC, the main psychoactive component of marihuana and hashish. Although the decarboxylation of Δ9‐THCA‐A to Δ9‐THC was assumed to be complete—which means that no Δ9‐THCA‐A should be detectable in urine and blood serum of cannabis consumers—we found Δ9‐THCA‐A in the urine and blood serum samples collected from police controls of drivers suspected for driving under the influence of drugs (DUID). For LC‐MS/MS analysis, urine and blood serum samples were prepared by solid‐phase extraction. Analysis was performed with a phenylhexyl column using gradient elution with acetonitrile. For detection of Δ9‐THCA‐A, the mass spectrometer (MS) (SCIEX API 365 triple‐quadrupole MS with TurboIonSpray source) was operated in the multiple reaction monitoring (MRM) mode using the following transitions: m/__z__357 → 313, m/__z__357 → 245 and m/__z__357 → 191. Δ9‐THCA‐A could be detected in the urine and blood serum samples of several cannabis consumers in concentrations of up to 10.8 ng/ml in urine and 14.8 ng/ml in serum. The concentration of Δ9‐THCA‐A was below the Δ9‐THC concentration in most serum samples, resulting in molar ratios of Δ9‐THCA‐A/Δ9‐THC of approximately 5.0–18.6%. Only in one case, where a short elapsed time between the last intake and blood sampling is assumed, the molar ratio was 18.6% in the serum. This indicates differences in elimination kinetics, which need to be investigated in detail. Copyright © 2007 John Wiley & Sons, Ltd.