The Nose Knows: Volatile profiling of cannabinoid-containing e-liquids toward canine detection.

Abstract

Over the past few years, semi-synthetic (SSCs) and synthetic cannabinoids (SCs) have entered the market through vaping e-liquids, a matrix drug detection dogs are not trained on. This study combines a survey of European dog handlers, behavioral trials with Belgian federal police drug- detection dogs, and volatile profiling of the e-liquids concerned. The volatile fraction of e-liquids containing semi-synthetic cannabinoids (SSCLs), synthetic cannabinoids (SCLs) or nicotine was sampled by dynamic headspace (D-HS) and analyzed by TD-GC-MS, then linked to the dogs' behavioral responses to identify potential markers. Although handlers are aware of this trend, few respondents give it specific attention. Trained on the most common drug classes, notably cannabis, dogs alerted to SSCLs in about a quarter of presentations, with no significant detection for SCLs. Beyond the shared background of propylene glycol and glycerin, the presence of SSCs or SCs reshapes the volatile composition: SSCLs are dominated by terpenes, while SCLs stand out through synthesis residues, among them dimethylformamide (DMF), a solvent used to dissolve the precursor, whose headspace presence signals the synthesis route. Dogs trained on cannabis generalize to SSCLs, detection tracking the resemblance of the terpene profile to cannabis. They do not detect SCLs. Several class-specific compounds were nonetheless identified as candidates for future training aids.