A rapid and convenient sample preparation method for the analysis of cannabinoids in oral fluid samples

Cannabis is the world's most used illegal drug. The main psychoactive component of cannabis is Δ9-tetrahydrocannabinol (THC). To aid the identification of cannabis-impaired individuals, a simple but effective workflow for reliable quantification of THC and its metabolites in oral fluid samples collected with the Greiner Bio-One Saliva Collection System is presented. Sampling involves rinsing the oral cavity with an extraction solution containing a citrate buffer stimulating salivary flow. Sample processing targeted the cannabinoid fraction interacting with proteins and other insoluble constituents that can be separated by centrifugation. Approximately 50% of the total amount of cannabinoids included in the oral fluid was recovered from the obtained pellet by extraction with acetonitrile. Liquid chromatography-tandem mass spectrometry was used for cannabinoid quantification. Fitness of the developed workflow for application in forensic and clinical cannabis testing was demonstrated by evaluating multiple performance parameters, including selectivity, linearity, limits of quantification (LOQs), accuracy, precision, matrix effects, extraction recoveries, process efficiencies and stability. Furthermore, sensitivity and specificity of the developed oral fluid-based cannabis test was demonstrated by analysing 195 samples collected either from opioid addicts or persons suspected of driving under the influence of drugs. The accuracy of identifying a person with the presence of THC in blood was found to be 97.9%.