Analysis of cannabis seizures by non-targeted liquid chromatography-tandem mass spectrometry

Due to the popularity of recreational cannabis use, contamination of this drug with diverse classes of chemicals, including pesticides, mycotoxins, and synthetic cannabinoids, has been identified as major threat for public health. For the detection of these compounds in seized cannabis, a screening workflow involving non-targeted liquid chromatography-tandem mass spectrometry (LCMS/MS) was developed. A Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method was used for the extraction of small bioorganic molecules from ground dried material. Instrumental analysis involved chromatographic separation of compounds and subsequent mass spectrometric detection. Collection of MS and MS/MS information was accomplished by data-dependent acquisition. Compound identification was primarily based on matching acquired MS/MS-spectra to several thousands of reference spectra stored in multiple libraries. Additionally, for selected cannabinoid and pesticide standards, a retention time library was developed. Performance of the workflow was evaluated for 182 pesticides. All tested pesticides were detectable at 5000 μg/kg, 94 % at 500 μg/kg, and 50 % at 50 μg/kg. The workflow was applied to the screening of seized cannabis samples. 41 out of 93 analysed samples (44 %) were tested positive for one or more contaminants impairing quality and/or safety of the material. The detected contaminants included a synthetic cannabinoid (5F-MDMB-PINACA), fifteen pesticide residues (boscalid, carbendazim, chlorantraniliprole, chlorpyrifos, chlorotoluron, cyprodinil, diflubenzuron, ethiofencarb sulfoxide, hexythiazox, iprodione, metalaxyl, pyrimethanil, terbutryn, thiophanate methyl, and trifloxystrobin), and a mycotoxin (sterigmatocystin).