Cannabis continues to be a highly abused recreational drug. The increasing number of states legalizing it for medical use, combined with the trend towards legalization for recreational purposes, means than analytical methods for the quantification of Δ-9-tetrahydrocannabinol (THC), and related cannabinoids continue to be necessary. In addition to urine and whole blood, there is a growing need for plasma and oral fluid specific analytical techniques. While THC and related compounds have some unique analytical challenges, the individual properties of these 4 matrices also need to be addressed during method development. This work details the optimization of methods for THC, 11-hydroxy Δ-9-THC (THC-OH) and 11-nor-9-Carboxy-Δ-9-THC (THC-COOH) in plasma, oral fluid (OF), whole blood and urine. This work details the extraction and analysis these compounds from all 4 matrices using a novel reversed-phase sorbent, followed by direct analysis by UPLC/MS/MS. Matrix specific adjustments in SPE protocols and chromatographic methods were employed to optimize each analysis.
For all 4 biological samples, Waters’ Oasis PRiME HLB µElution plates were used: All samples were pretreated as appropriate for each matrix. The pretreated samples were then directly loaded onto the µElution plate without conditioning or equilibration. Elution solvents were optimized for each matrix. The final eluates were diluted with water for direct LC/MS/MS analysis without evaporation/reconstitution.
Analysis was rapid and highly consistent, with all analytes eluting within 3 minutes. Excellent recoveries and minimal matrix effects were obtained on all four biological samples. More than 90% of phospholipids were removed from the whole blood and plasma samples compared to protein precipitation. Quality control values were accurate and precise for all analytes in all 4 matrices. All results were within 12% of expected values and %RSDs were under 10%. The excellent accuracy and precision demonstrate the consistency and robustness of the methods.
This application highlights the quantification THC and its metabolites in multiple biological matrixes. Matrix specific optimization strategies, resulting in consistent recoveries and low matrix effects, contributed to method consistency and robustness. The μElution format enabled the direct injection of extracts without evaporation or reconstitution, minimizing the risk of nonspecific binding. The method also eliminated phospholipids that would normally coelute with analytes of interest resulting in decreased matrix effects.