This application note details the extraction of THC-OH, THC-COOH, and THC from oral fluid samples using a novel SPE sorbent, Oasis PRiME HLB, in a μElution format for forensic toxicology applications.
This sorbent enabled the elimination of conditioning and equilibration steps, simplifying the extraction procedure and speeding up the sample preparation workflow. In addition, the μElution format enabled the direct injection of extracts without evaporation or reconstitution, minimizing the risk of nonspecific binding and sample losses. The unique nature of oral fluid resulted in some ion suppression that was not seen in other matrices. In order to overcome this signal suppression, a CORTECS C18 Column was utilized for high efficiency and the SPE wash step was optimized with the addition of 5% strong ammonia. These changes resulted in a method with negligible matrix effects (<10%) and calibration curves R2 value all greater than 0.999.
In conclusion, Oasis PRiME HLB has been successfully used to achieve consistent recoveries with minimal matrix effects as well as accurate quantification 4 orders of magnitude from oral fluid samples.