A Simple Isocratic HPLC Method for the Quantitation of 17 Cannabinoids

Although cannabis has been used for several thousand years, the exact composition of the cannabinoids patients are administered for different symptoms has remained largely unknown. While this absence of catalogued information may be accepted in some cultures, the use of cannabis as a human product in the registered medicines setting requires knowing its composition so that doses can be standardised between patients. This is particularly so in clinical trials that are currently under way to determine the efficacy of a product. Although the major cannabinoids of interest to prescribers are well known – tetrahydrocannabinol and cannabidiol and the corresponding acids tetrahydrocannabinolic acid and cannabidiolic acid, the cannabis plant contains many more phytocannabinoids. We have developed and validated a robust and fast (11 min) isocratic HPLC method for the analysis of 17 phytocannabinoids. The method had an analytical range of 1–150 μg mL−1 for tetrahydrocannabinolic acid and cannabidiolic acid, 0.5–75 μg mL−1 for tetrahydrocannabinol and cannabidiol, and 0.5–20 μg mL−1 for the remaining 13 cannabinoids. The method had excellent repeatability with a relative standard deviation of between 5 and 14 % and a bias of between –8.6 and 6 % for the 17 cannabinoids. The method was applied to the analysis of medicinal cannabis products, including both flos and oils with results matching the supplier’s certificate of analysis. This simple fast isocratic method with basic HPLC equipment can be easily transferred to any analytical laboratory interested in the identification and quantitation of cannabinoids.