A research note: the outcome of GC/MS/MS confirmation of hair assays on 93 cannabinoid (+) cases.

This article reports the outcome of gas chromatography/tandem mass spectrometry confirmations for THC and carboxy-THC on 93 hair samples screened by RIA for cannabinoids. The samples were taken from probationers in Pinellas County, FL, who voluntarily provided the research staff with six hair and six urine specimens, collected at 1-month intervals. There were 40 samples that were RIA (+), urinalysis (-). Samples were selected which had cannabinoid (+) outcomes for hair, urine, or both. The THC and/or the carboxy-THC was (+) on confirmation. Of these 40 samples, 22 were (+) for both THC and carboxy-THC, 15 were (+) for THC but not carboxy-THC, and three were carboxy THC (+), but THC (-). Only one sample had a (+) RIA, but was (-) for both THC and carboxy-THC on confirmation. RIA detection of cannabinoids was confirmed in nearly all cases. Most cases that were RIA (-) but urine (+) were cannabinoid (+) when analyzed by GC/MS/MS.