Driver breath measurement of marijuana intoxication by infrared spectroscopy

The intoxicating effects of marijuana are of public safety concern. With the expected increase in the use of this substance it is important to provide law-enforcement officials with a simple driver test for its detection. Because of the presence of the intoxication agent tetrahydrocannabinol (THC) vapor in the exhaled breath of marijuana users, it is possible to confirm marijuana intoxication via breath test, but this test must be simple, rapid and reliable. Since the unique infrared spectral signature of THC is known, it is possible to quantitatively measure the presence of this compound in exhaled breath by means of infrared absorption spectroscopy. Recent developments make it possible to rapidly analyze the spectral absorption characteristics of THC vapors introduced into an optical adsorption cell. Phase I will demonstrate concept feasibility by using an infrared absorption spectroscopy system to measure the absorption spectrum of marijuana smoke over a broad range of quantitatively established THC concentrations. Phase II will refine instrument design and validate its efficacy by testing the exhaled breath of an ensemble of marijuana users at various time intervals after smoking cessation. Successful completion of both phases of this project will pave the way for rapid commercialization of this new instrument.