Determination of pesticides residue in cannabis, cannabis extract and cannabis oil by gas chromatography tandem mass spectrometry technique

Pesticide residues analysis in cannabis has become a major interest in Thailand due to recent legalization and decriminalization of cannabis for medicinal uses since February 2019. To meet regulatory and quality control standards, cannabis raw materials and products should be tested for pesticides with action limits set by Thai Herbal Pharmacopeia. In this study, pesticides found in cannabis, cannabis extract, and cannabis oil samples submitted by government agencies have been reported. A quantitative and sample preparation method was established and validated following the EN 15662 QuEChERS for cannabis and EURL-FV (2012-M6) for cannabis extract and cannabis oil analysis. The identification of 122 pesticides in the sample was performed by scheduled selected reaction monitoring technique via GC-MS/MS using matrix-matched calibration curves. The method LOD and LOQ in 3 products were 0.03 and 0.05 mg/kg respectively with recoveries situated between 70% and 120%, and within laboratory relative standard deviations below 20%. According to the requirements of international pharmacopoeias and food regulatory agencies, the developed method was compiled since cannabis was found in both categories, as herbal remedies and foods. Overall, 8 pesticides belonging to different chemical classes were identified in 69 of 85 samples (81.2%) ranging from less than 0.05 to 77.5 mg/kg. The occurrence of most pesticides was exceeded the action limit. Generally, the samples of illegal cannabis contained toxic pesticides used in cultivation which were not safe for the production of cannabis-derived pharmaceutical drugs. Therefore, the strategic control for organic or medical-grade cannabis plantation should be enforced.