Abstract: A determination method for Δ9-tetrahydrocannabinol (THC) in edible vegetable oil was developed on the basis of ultra-high performance liquid chrmatography-electrospray tandem mass spectrometry (UPLC-MS/MS) under negative ion mode using electrospray ionization (ESI) source. THC was extracted with methanol and then purified by LC-alumina-N solid phase extraction column. Qualitative and quantitative analysis were carried out for the analyte under a MRM mode after THC was separated on Waters ACQUITY UPLCTM BEH C18 (1.7  μm, 2.1 mm×100 mm) column. The limit of detection (LOD) of the developed method was 0.15  μg/kg and the limit of quantification (LOQ) was 0.45  μg/kg for THC. Quantitative analysis was corrected by internal standard method using delta 9-THC-D3 as internal standard. Average recovery rate of THC varied from 68.0%－110.0% with relative standard deviation ranging from 8.8%－18.1% at three spiked levels. Therefore, the developed method meets the requirements for the determination of THC in edible vegetable oil.

Key words: edible vegetable oil, Δ9-Tetrahydrocannabinol, ultra-high performance liquid chromatography-electrospray tandem mass spectrometry (UPLC-MS/MS), negative ion mode