High-throughput LC-PDA method for determination of Δ9-THC and related cannabinoids in Cannabis sativa

Before the passage of the Agriculture Improvement Act of 2018, more commonly referred to as the 2018 Farm Bill, forensic laboratories were only required to perform qualitative measurements to confirm the identity of seized plant samples as Cannabis sativa (hemp or marijuana). The new law defines hemp at a federal level as Cannabis sativa containing 0.3 % or less Δ⁹-THC. Because forensic laboratories were not adequately equipped with the proper methods or training to meet these requirements, significant backlogs in casework resulted. The National Institute of Standards and Technology (NIST) responded by providing analytical tools to the forensic community. An accurate and precise method was previously developed to determine Δ⁹-THC, Δ⁹-THCA, and total Δ⁹-THC in botanical samples based on liquid chromatography with photodiode array detection (LC-PDA). Cannabis plant samples were ground and extracted with methanol using routine laboratory equipment. The original sample preparation procedure was time-consuming, taking over 70 min. The method described here has been optimized with the time required for sample preparation and LC-PDA analysis has been reduced to less than 30 min.