The Evolving Landscape of THC Drug Testing, Delta-8 vs. Delta-9

When performing drug testing for THC, the carboxy metabolite is historically the analyte used to determine cannabis usage. This compound is detectable in urine or blood for several weeks, but it can be challenging to determine if a user is intoxicated at the time of testing. Labs may be interested in testing for the hydroxy metabolite, the intermediate between THC and the carboxy metabolite. This intermediate is useful in determining time of consumption. Delta8-THC is an isomer of delta9-THC that also has psychoactive effects. Chromatographic separation of delta8/9-THC and their respective metabolites is required due to their nearly identical structures. Three column chemistries were investigated in this study for the analysis of delta8/9-THC and their metabolites. Biphenyl, ARC-18, and FluoroPhenyl stationary phases were tested on a 100 x 2.1 mm column dimension using water and methanol as mobile phases, both modified with 0.1% formic acid. The FluoroPhenyl column shows great selectivity for the target analytes and resolved all three pairs of isomers with a 12-minute cycle time. This method could be used to determine THC isomers and metabolite levels in biological fluids.