Factors influencing the recovery of Δ9-tetrahydrocannabinol, cannabidiol, and cannabinol from a breath sampling device

Cannabinoids can be captured from breath after cannabis use, but sample processing varies between studies, even when using the same sampling device. The Breath Explor impaction filter device has been used to capture THC in breath after cannabis use in multiple studies, but processing differed in solvent type, keeper addition, and concentration method. In this study we test the effect that container material, vacuum concentration, keeper, elution solvent, cannabinoid mass, agitation, and elution time have on the recovery of Δ9-tetrahydrocannabinol, cannabidiol, and cannabinol from spiked breath samples. Only container material and keeper had a significant impact on recovery, although limiting the use of plastic vials, one of the two container materials studied, did have some mitigating effects. Despite these two factors having a significant effect, the recovery of cannabinoids remained relatively low. Further investigation showed that our process for the preparation of spiked breath samples, specifically the complete evaporation of a small volume of spike solvent, leads to large cannabinoid losses. As recently published high-accuracy vapor pressure data indicates that these cannabinoids should be considered semi-volatile, a microelution process was additionally explored as it requires less solvent and therefore no concentration is necessary during sample processing. The microelution process resulted in similar or higher recoveries of cannabinoids as compared to the large volume elution process, suggesting that it is a superior processing method in terms of recovery and processing time.