Development of quantitative method for Δ⁹-THC in cannabis infused foods using GC-FID and QuEChERS

Abstract

 We have developed a quantitative method that uses GC-FID and QuEChERS to measure Δ-9-tetrahydrocannabinol (Δ⁹-THC) in cannabis-infused foods. Reported methods for the analysis of cannabis-infused foods typically use liquid chromatography, but obtaining Δ⁹-THC used in these methods, with the certified concentration, is difficult in Japan. Therefore, we attempted to apply a method, obtained from the United Nations Office on Drugs and Crime, that allows the quantitative analysis of Δ⁹-THC in herbal cannabis, hashish, and liquid using cannabinol as the reference material. In this study, the QuEChERS method, which is widely used in food analysis, was adopted. The EN 15662 salt method (EN salt method) and Enhanced Matrix Removal-Lipid method (EMR-Lipid method) were compared using recovery tests for Δ⁹-THC added to four types of food samples. The EN salt method was found to be superior to the EMR-Lipid method for some foods. A similar test was conducted on six different types of foods using the EN salt method. The recovery was 95.2% to 113.5%. The precision was tested at two levels of Δ⁹-THC content in three trials over three days. The intra-day precision was 9.8% and 1.4% for 0.1 mg/g and 1 mg/g Δ⁹-THC, respectively. The inter-day precision was 16.6% and 4.4% for 0.1 mg/g and 1 mg/g Δ⁹-THC, respectively. Cannabis-infused brownie was homogenized, divided, and tested in three laboratories. The average values of Δ⁹-THC content at the three laboratories were 0.33, 0.43, and 0.48 mg/g. We analyzed Δ⁹-THC content in 13 cannabis edibles seized in Japan. The overall Δ⁹-THC content ranged from 0.33 mg/g to 7.14 mg/g, and the content per piece ranged from 4.3 mg to 13.9 mg. This study demonstrates a useful method for the quantification of Δ⁹-THC in cannabis-infused foods.