The passing of the Farm Bill (2018) resulted in a major change to the legal status of cannabis, reclassifying hemp and removing it from the Controlled Substances Act (CSA) [1]. This bill differentiates hemp and marijuana from one another based on the amount of delta-9-tetrahydrocannabinol (∆9-THC) present; stating that to be classified as hemp there must be no more than 0.3% ∆9-THC by dry weight present. Because of this new distinction, labs are now faced with the new issue of having to determine whether a seized sample is marijuana or hemp. In this vein, low THC and relatively high cannabidiol (CBD) is indicative of hemp. Therefore, the presence – or lack – of THC is no longer an adequate indication of whether a sample is controlled, so proper testing and quantitation techniques must be relied upon [2]. This project compared different extraction methods used for the quantification and detection of cannabinoids to help overcome this differentiation problem in complex gummy matrices.

In this study, numerous extraction methods were evaluated on various gummy samples to examine cannabinoid recovery. A modified LC-PDA method [2], with extended purge time to reduce the carryover of matrix components, was used to screen gummy samples for 11 different cannabinoids. Extraction methods were then compared to one another across different cannabis-containing gummies and a suite of non-cannabis gummy samples spiked with known concentrations of cannabinoids to assess recovery, repeatability, and to look for potential interferences.
Sample dissociation methods investigated included enzyme digestion (α-amylase), cryo-grinding, and agitation/shaking with and without heating. Dissolution was generally done in an aqueous solution, with the optional addition of base (ammonium hydroxide), followed by the addition of acetonitrile, or methanol to extract cannabinoids. Liquid-liquid extraction (LLE) via the Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method was investigated for acetonitrile extractions.

Three selected screened extraction methods were then applied to a suite of commercial and seized gummy samples with varying cannabinoid concentrations. Repeatability and detection of key cannabinoids such as cannabidiol (CBD) established these as effective, laboratory-applicable methods that apply to a wide range of gummy samples. It was found that the investigated amylase digestion followed by the addition of acetonitrile and QuEChERS performed the best across almost all sample types and cannabinoids analyzed. This extraction method had percent RSDs that typically ranged from 2 to 10%. In comparison, the other selected extraction methods yielded lower recoveries. Method comparisons and the results of these studies will be presented.

References:
[1] Abernethy, A. (2019, July 25). Hemp production and the 2018 farm bill. U.S. Food And Drug Administration. https://www.fda.gov/news-events/congressional-testimony/hemp-production-and-2018-farm-bill-07252019

[2] Study Reveals Inaccurate Labeling of Marijuana as Hemp | National Institute of Justice. (n.d.). National Institute of Justice. https://nij.ojp.gov/topics/articles/study-reveals-inaccurate-labeling-marijuana-hemp