THCVA-A - a new additional marker for illegal cannabis consumption

The aim of the present investigations was to find markers for differentiating between the consumption of illegal cannabis products and legal medication containing fully synthetic Δ9-tetrahydrocannabinol (Δ9-THC), e.g., Marinol capsules. Δ9-Tetrahydrocannabinolic acid A (Δ9-THCA-A) and Δ9-tetrahydrocannabivarinic acid A (Δ9-THCVA-A) were taken into consideration for analysis, because these substances are the precursors of Δ9-THC and Δ9-tetrahydrocannabivarin (Δ9-THCV) in plant material of Cannabis sativa and are not contained in medical THC formulations. Whereas Δ9-THCA-A is an already well investigated substance, there is little analytical data on Δ9-THCVA-A. The reason for the presented investigations was a case in which a man was tested positive for Δ9-THC during a routine traffic control claiming that the positive serum sample resulted from the intake of a THC medication (Marinol) and not from consuming illegal cannabis products. Sample preparation consisted of a protein precipitation with acetonitrile. Analysis was carried out on a Thermo Fisher LCQ Deca ion trap LC-MS-MS-system using electron spray ionization (ESI) in negative mode. MS(2)- and MS(3)-full scan spectra were recorded for Δ9-THCA-A and Δ9-THCVA-A starting from [M-H](-). Reference spectra were obtained by measuring a Δ9-THCA-A reference solution and an ethanolic cannabis extract for Δ9-THCVA-A as there is no reference material for this cannabinoid available on the market yet. Main transitions for Δ9-THCA-A were m/z 357→313 and 339 in the MS(2)-spectrum and m/z 313→245 and 191 in the MS(3)-spectrum. Fragmentation pattern of Δ9-THCVA-A was identical with a difference of 28 amu less for the precursor ion as well as the fragments due to a shorter alkyl side chain in the molecule (MS(2): m/z 329→285 and 311; MS(3): m/z 285→217 and 163). The two plant cannabinoids Δ9-THCA-A and Δ9-THCVA-A could be detected in the serum sample by LC-MS-MS which proved the intake of illegal cannabis products derived from plant material of C. sativa in the described case.