Chemical Foundations of a Cannabis Breathalyzer

Cannabis decriminalization for medicinal and adult recreational uses by state ballot initiatives has created an urgent need for roadside detection of cannabis impairment. The proposed work, in three phases, lays the chemical foundation for industry to develop a cannabis breathalyzer that identifies impaired drivers, improving public safety and supporting the criminal justice system. Current breathalyzer technology has been limited to the detection of delta-9-tetrahydrocannabinol (THC) potentially linked to recent smoking or vaping, ignoring the presence of a complex mixture of biomarkers and other chemicals in breath. Furthermore, there has been no published study identifying the chemical signature or biomarkers of intoxication in exhaled breath of cannabis users. Phase I of our work will fill this knowledge gap while evaluating two existing devices for breath collection. Collaborators at the University of Colorado will provide exhaled breath samples from human subjects. We will conduct quantitative analysis of samples for targeted cannabinoids, terpenoids, and metabolites, as well as an untargeted, chemometric analysis. Blood composition and impairment will be measured alongside breath. THC and other cannabinoids are non-volatile and chemically unstable, creating an as-yet unsolved measurement challenge that did not exist for the alcohol breathalyzer. In Phase II, we will use our unique expertise in developing new methods· for property measurements of large and unstable compounds to measure vapor pressures and blood-air partition coefficients of the compounds we identify in Phase I. These data may inform correlations between breath and blood composition that we observe in the collaborative clinical studies, which also include important person-to-person variation. Phase Ill involves rigorous characterization of current and potential device materials. We will innovate powerful nuclear magnetic resonance techniques to measure competitive adsorption and desorption properties for cannabis compounds and breathalyzer materials. We will also use our knowledge of vapor pressures to deliver a simulated breath with known composition to the devices tested in Phase I in order to assess their overall recovery. Although the clinical, pharmacokinetic, thermophysical, and materials knowledge we generate will be powerful, and both methods and data will be made available to the scientific community, the ultimate positive impact on criminal justice system will be a breathalyzer device that leverages the optimal materials and collects the right target compounds to detect intoxication. We envision a multisector collaboration with the breathalyzer device industry and our university colleagues as a path forward from this proposal.