The emergence of Δ9-tetrahydrocannabinol (Δ9-THC) isomers, particularly Δ8-tetrahydrocannabinol (Δ8-THC), have created analytical challenges. Traditional methods for separating Δ8-THC and Δ9-THC do not adequately resolve these metabolites, resulting in quantitation issues and the inability to determine an accurate value for one or both isomers. This issue is especially prevalent in urine samples where these metabolites may be detected at high concentrations.
The primary objective of this study was to evaluate the capability of different HPLC column chemistries to separate Δ8-THCCOOH and Δ9-THCCOOH.
Multiple LC-MS/MS methods were developed and optimized to separate Δ8-THCCOOH and Δ9-THCCOOH using a Raptor Biphenyl (2.7 μm, 100 x 2.1 mm), Raptor C18 (2.7 μm, 100 x 2.1mm), and a Raptor FluoroPhenyl (2.7 μm, 100 x 2.1 mm). Each method used water and methanol as MPA and MPB respectively, both acidified with 0.1% formic acid.
Of the three stationary phases tested, the Raptor FluoroPhenyl column chemistry provided optimal separation of Δ8-THCCOOH and Δ9-THCCOOH in the shortest analysis time. The separation completely resolved the isomers, preventing quantitation errors caused by the analytes interfering with each other.
