Abstract: Abstract： Objective To establish a high performance liquid chromatographic （HPLC） method for simultaneous determination of three effective constituents, including tetrahydrocannabinol （THC）, cannabidiol （CBD） and cannabinol （CBN） in Cannabis plants. Methods A C18 column was used in this study, and acetonitrile-phosphate buffer （0.015 mol/L KH2PO4） was used as mobile phase at a flow rate of 1.0 mL/min. At a detection wavelength of 220 mm, UV absorption spectra were collected at the wavelength range of 190-400 nm, and the spectra and retention time were counted as qualitative evidence. Results THC, CBD and CBN could be well separated by this method. Three components had good linear relationship in the range of 0.4-40 μg/mL （R2≥0.999 3）. The recoveries were over 87%. The limits of detection were 1.8 ng, 2.0 ng and 1.3 ng, respectively. The relative standard deviation （RSD） were less than 5% for both inter-day and intra-day precisions. Conclusion Reversed-phase HPLC method is simple, rapid and accurate, and it is suitable for the qualitative and quantitative detection of THC, CBD and CBN in Cannabis plants.

Key words: forensic toxicology, high performance liquid chromatography, Cannabis, tetrahydrocannabinol, cannabidiol, cannabinol