Determination of cannabinoids in illegal e-cigarette fluids in Korea by LC-MS/MS

Abstract

Recently, the use of illegal e-cigarette containing THC is prevalent in Korea. In this study, the quantitative analysis was performed to measure the contents of cannabinoids in 15 e-cigarette fluids of which 4 was seized in 2016, 1 in 2017 and 10 in 2021. In addition, to investigate the adulteration of △9-THC with the synthetic △8-THC, the concentrations of △8-THC, △9-THC, CBD and CBN were determined in 15 e-cigarette fluids by LC-MS/MS. Of total 15 samples, 5 samples were of cartridge type, 8 samples were of viscous liquid type and 2 samples were of oil type. The samples were diluted to the concentration of 1 mg/mL with methanol and then diluted 100-fold again. By adding the internal standard (Δ9-THC-d3), the mixture was injected into LC-MS/MS. (Agilent 1260 infinity liquid chromatography system and AB3200 Qtrap tandem mass spectrometry). Target compounds were separated on InfinityLab Poroshell 120 EC-C18 column (2.1 × 150 mm, 2.7 μm) and mobile phase was 0.1% formic acid in water and 0.1% formic acid in acetonitril. The method was validated for precision, accuracy and recovery. △8-THC, △9-THC, CBD and CBN were well resolved in this condition. The validation results demonstrated the accuracy of 98 to 103% and the precision of 8 to 14%. The contents of △8-THC in 15 samples ranged from 0.014 mg/mL to 0.235 mg/ml, 0.011 mg/mL to 0.375 mg/mL for △9-THC, 0.003 mg/mL to 0.053 mg/mL for CBD and 0.001 mg/mL to 0.015 mg/mL for CBN respectively. The amounts of total THC (△8-THC and △9-THC) were between 2.6 to 42.5% in 15 samples. Among them, one sample contained over 40% of total THC, 5 samples were between 30 to 40%, 3 samples were between 20 to 30% and 6 samples were lower than 10%. There are 10 samples that were over 20% of total THC, 9 highly viscous liquid type and 1 oil type, and 5 samples that contained less than 10% of THC, 4 cartridge type and 1 oil type. The ratio of [△8-THC]/[△9-THC] ranged from 0.04 to 1.95 in all 15 samples. Among them, the ratio of 12 samples were between 1.06 to 1.95 indicating the higher contents of △8-THC than △9-THC. It was believed that △9-THC was substituted with △8-THC by purposely converting or modifying from △9-THC or CBD because the amount of △8-THC found in cannabis plant is generally less than 1%. The ratio of [CBN]/[△9-THC] were between 0.04 to 13.57 in 15 sample, but particularly 3 samples seized in 2016 showed pointedly higher ratio of 1.91 to 13.57 signifying the waning of freshness. △8-THC, △9-THC, CBD and CBN were well quantitated in 15 e-cigarette fluids by LC-MS/MS. The contents of THC were dispersed in wide range with the total THC (△8-THC and △9-THC) of 2.6 to 42.5% in fluids. However the ratio of [Δ8-THC]/[Δ9-THC] in 12 samples showed over 1.0 demonstrating the amount of Δ8-THC was larger than that of Δ9-THC. It was assumed that the adulteration of △9-THC with the synthetic △8-THC by the conversion of CBD or conversion of Δ9-THC. [CBN]/[Δ9-THC] in the samples of 2016 was significantly higher than that of the later year samples, which was thought to be the decrease of freshness.