Potency Analysis of Medical Marijuana Products from New York State

Introduction: In the United States, medical marijuana programs have been established in 29 states and the District of Columbia. In 2014, New York State (NYS) approved medical marijuana legislation, and its program became fully operational in January of 2016. Products manufactured under the auspices of the program may be used by certified patients in NYS for the treatment of 1 of 12 qualifying medical conditions. The NYS statute requires rigorous testing of each product lot manufactured in the state for its cannabinoid profile, bacterial and fungal contamination, mycotoxins, heavy metals, plant-growth regulators, and pesticides. Here, we report on the analysis of product cannabinoid profiles. Methods: A method employing a simple extraction/dilution technique and reversed-phase high-performance liquid chromatography with photodiode array detection (HPLC-PDA) was developed for the analysis of 10 cannabinoids: cannabidiolic acid, cannabigerolic acid, cannabigerol, cannabidiol (CBD), tetrahydrocannabivarin, cannabinol, Δ⁹-tetrahydrocannabinol (Δ⁹-THC), cannabichromene, cannabidivarin, and Δ⁹-tetrahydrocannabinolic acid-A. The method employed internal standard quantitation and incorporated a surrogate to monitor extraction efficiency and analytical recovery. Results: The HPLC-PDA method was validated using sample matrices composed of medium-chain triglycerides, hemp oil, sesame oil, and an ethanol-propylene glycol tincture. Limits of detection, limits of quantitation, accuracy, precision, and inter- and intraday reproducibility were found to be highly satisfactory. The validated method has been used to analyze over 3500 samples from over 700 lots of medical marijuana products manufactured in NYS from January 2016 through April 2018. Quality-control data showed quantitative spike recoveries and, for the analysis of samples from the same lot, the coefficients of variation for the principal analytes, Δ⁹-THC and CBD, averaged <3%. Using the HPLC-PDA method, the NYS medical marijuana products were analyzed to verify the potencies on the product labels and to determine the stability of the products. Conclusions: An HPLC-PDA-based method was developed, validated, and employed to analyze 10 cannabinoids in a variety of medical marijuana products. The method has proven to be accurate, precise, stable, and very robust. Its use is an integral part of the NYS Medical Marijuana program for validation of the content and consistency of medical marijuana products.