Study of the Detectability of Controlled Substances on Breath

Bryant, P. J.; Valentine, J. L. (Jimmie Lloyd), 1940-; Gutshall, P. L.; Gan, O. H. M.; Driscoll, P. · 1975 · ROSA P / United States. National Highway Traffic Safety Administration

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Summary

This 1975 study, conducted by the University of Missouri for the National Highway Traffic Safety Administration, addresses the challenge of detecting controlled substances, specifically marijuana, on human breath. While breath analysis is standard for alcohol due to its volatility, detecting larger drug molecules like delta-9-tetrahydrocannabinol (Δ9-THC) presents significant difficulties because of low plasma concentrations and structural similarities with other cannabinoids. The research aimed to develop a sensitive, selective method for quantifying Δ9-THC in breath and to validate its applicability for roadside screening of drivers. The researchers developed an analytical protocol combining high-pressure liquid chromatography (HPLC) with mass spectrometry (MS). To achieve the necessary sensitivity and selectivity, they utilized a gradient elution program to separate Δ9-THC from other marijuana constituents and employed a deuterated internal standard (d3-Δ9-THC) with a peak-matching ion-counting technique for precise quantification. Two breath collection devices were designed and tested: a portable polyethylene foam wafer mask and a cold-trap ethanol breath tube. Human studies involved volunteers smoking marijuana cigarettes containing approximately 20 mg of Δ9-THC. Breath samples were collected at varying intervals post-smoking using these devices, alongside blood and saliva samples for correlation. The study successfully detected and quantified Δ9-THC in breath for up to 24 hours after smoking. A significant finding was the identification of a previously unreported marijuana metabolite (designated tR 23.1) present in the breath of all smokers. This metabolite persisted for at least five days, far longer than Δ9-THC, and appeared in concentrations high enough to be detected by UV spectrophotometry alone, without requiring mass spectrometry. The presence of this metabolite unequivocally identified marijuana users, even those who had smoked prior to the study session. Correlations between blood and breath levels indicated that the lungs serve as an excretory route for these compounds. The ethanol breath tube collected slightly higher amounts of Δ9-THC and additional metabolites compared to the foam wafer, though the wafer offered superior portability and stability for transport. The findings demonstrate that Δ9-THC and its metabolites can be reliably detected in human breath, offering a potential non-invasive method for assessing marijuana use and intoxication. The long persistence of the tR 23.1 metabolite suggests it could serve as a definitive marker for recent use, while combined analysis of the metabolite and Δ9-THC could estimate the time elapsed since smoking. The study concludes that the developed technology, particularly the ability to detect the metabolite via simpler HPLC-UV methods, holds promise for practical roadside screening applications.

Key finding

A previously unreported marijuana metabolite was detected in human breath for at least five days after smoking, while delta-9-THC remained detectable for up to 24 hours.

Methodology

lab_experiment

Sample size: 26

Provenance

The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed. Discovered via bulk_ingest_rosap on 2026-05-23 (6 acquisition events logged).

Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

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• cannabis