The Use of UCT's ZSTHC020 in German Cannabinoids Study

Of all the analytes that Forensic Toxicologists are asked to test for, THC still remains high on the list. In a study published in the International Journal of Legal Medicine (DOI 10.1007/s00414-016-1368-6) from the Institute of Legal Medicine (Muenster, Germany), a procedure employing UCT’s Flagship THC SPE column (ZSTHC020)  was developed and validated for analysis of cannabinoids.  Primary focus was on extensive and effective matrix reduction in order to ensure constant good results in selectivity and sensitivity regardless of the applied measuring technology. The high quality extraction was obtained by the use of an mixed-mode anion exchange sorbent (ZSTHC020) and the purposive ionic interaction between matrix components and this sorbent material. In a first step, the neutral cannabinoids Δ9-tetrahydrocannabinol (THC) and 11-hydroxy-Δ9-tetrahydrocannabinol (11-OH-THC) were eluted, leaving 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) and the main interfering matrix components bound to the AXS. In a second step, exploiting differences in pH and polarity, it was possible to separate matrix components and THC-COOH,thereby resulting in a very clean elution of THC-COOH into the same collecting tube as THC and 11-OH-THC. Analysis was performed with  gas chromatography with single quadrupole mass spectrometry, this two-step elution allows for an obvious decrease in number and intensity of matrix interference in the GC-MS chromatogram. Hence, in both plasma and serum, the SPE extracts resulted in very good selectivity. Limits of detection and limits of quantification were below 0.25 and 0.35 ng/mL for the neutral cannabinoids in both matrices, 2.0 and 3.0 ng/ mL in plasma and 1.6 and 3.3 ng/mL in serum for THCCOOH. The recoveries were ≥79.8 % for all analytes. Interday and intraday imprecisions ranged from 0.8 to 6.1 %. This methodology demonstrates why UCT’s SPE sorbents are regarded by the worlds forensic scientists as the “go to” SPE products when the highest quality results are required for analysis.