Chemical Foundations for a Cannabis Breathalyzer (Final Research Report)

Published

March 1, 2024

Author(s)

Tara Lovestead, Jason A. Widegren, Kavita Jeerage

Abstract

Our ultimate goal is to support the reliable identification of recent cannabis use by developing an infrastructure for evaluation, calibration, and quality control of cannabis breathalyzers akin to that which exists for alcohol breathalyzers. The primary psychoactive molecule in cannabis, -9-tetrahydrocannabinol (THC), is semi-volatile based on challenging vapor pressure measurements made prior to the start of this project [1], and is lipophilic. The objectives of this project were, first, to identify sources of uncertainty in the capture of semi-volatile cannabinoids from breath through the investigation of one device, an impaction filter device containing replicate filters, and second, to develop robust, low-uncertainty methods to rapidly measure the volatility, or vapor pressure, of cannabis-associated compounds that might be found in breath. Human studies are used to identify cannabis-associated compounds in breath, their concentrations, and sampling challenges in the field. However, ground truth is unknown and human studies cannot be the sole means of device evaluation. Developing reference materials and delivery systems to deliver breath surrogates with known compound quantities requires relevant thermophysical properties, especially vapor pressure, to understand behavior during storage and delivery. Devices with different modes of action can be studied through human studies and numerical simulations. During this project, we utilized an impaction filter device designed to capture aerosols from breath. We examined the effect of aerosol diameter and fluid velocity on aerosol capture as a means to identify important parameters to control during human studies or when delivering breath surrogates containing aerosols. These data are essential steps towards prototyping reference materials and delivery systems for establishing ground truth for the performance of any device intended to determine recent cannabis use.

Citation

National Institute of Justice Publications Listing

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https://nij.ojp.gov/library/publications/list

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Citation

Lovestead, T. , Widegren, J. and Jeerage, K. (2024), Chemical Foundations for a Cannabis Breathalyzer (Final Research Report), National Institute of Justice Publications Listing, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=957196, https://nij.ojp.gov/library/publications/list (Accessed November 21, 2024)