Detection and quantification of 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid in hair by GC/MS/MS in negative chemical ionization mode (NCI) with a simple and rapid liquid/liquid extraction

Introduction: The fine detection of 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid (THCCOOH) in hair matrix remains one of most important topics in hair analysis. This revelance lies in the necessity to obtain evidence of effective drug comsumption and dispel any doubt of environmental contamination. THCCOOH is the highest and mainly represented delta9-THC metabolite, but its concentration in hair is very low. A sensitive method for quantitative determination of THCCOOH in hair is developed. As fist step, the method is tested with different SPE/LLE conditions, but the best result wereobtained with a simple ad hoc LLE extraction. The final method was fully validated, evaluating parameter like extraction recovery, linearity, specificity and sensitivity. More than one hundred hair samples were then analyzed with the validated method. Data analysis was performed so as to determine respective concentrations of the metabolite and active molecule.