Fast LC-MS/MS analysis of cannabinoids in dried blood spots for roadside testing

Cannabis is the most used drug of abuse (DoA) around the world. Due to this fact and its high potential for the impairment of driving skills, it is also one of the DoAs most frequently involved in street accidents. The main active Cannabis compound is generally considered Δ9-tetrahydrocannabinol (or THC), whose presence in blood can be taken as a marker of recent Cannabis intake. The carboxylated metabolite (THC-COOH) is inactive and cannot be taken as a marker of recent exposure or of consciousness alteration. The intermediate hydroxylated metabolite (THC-OH), which is still pharmacologically active, represents a necessary step in the formation of THC-COOH and for this reason it is a good marker of recent intake. Thus it is evident that only the simultaneous determination of all three analytes, the parent THC and the metabolites THC-OH and THC-COOH, can assure a complete and balanced evaluation of the current state of intoxication, or lack thereof, of individuals suspected of driving under the influence of psychotropic drugs (DUI). As a contribution toward this goal, an original LC-MS/MS method has been developed for the analysis of the three cannabinoids, coupled to the use of dried blood spots (DBS) as the testing matrix. DBS, produced by puncturing a finger and blotting the resulting blood drops onto special filter paper, are a very promising matrix for roadside testing, mainly due to the fact that they can be obtained after a fast and easy sampling and do not need any particular care during transportation and storage. The analytical results are very promising and further assays are underway, in order to fully validate the method.