A Comparison of Cannabis Potency Extraction Methods

Introduction

With the increasing prevalence of the legalization of cannabis at the state level, including industrial hemp, the need for extraction methods that accurately measure the cannabinoids in cannabis and its products continues to grow. Potency methods are of interest because they can determine the legality of the material, as some regulations require industrial hemp to contain less than 0.3% of Δ9-tetrahydrocannabinol (D9-THC) and tetrahydrocannabinolic acid (THCA) combined on a dry weight basis. Furthermore, the determination of the cannabinoid levels gauge whether materials can be used medicinally or recreationally, affecting the price of the dried plant material and its products. The five major compounds of interest in cannabis are D9-THC, THCA, cannabinol (CBN), cannabidiol (CBD), and cannabidiolic acid (CBDA). However, there are many other cannabinoids of interest.

Cannabis and its various products have proven to be challenging matrices. A major difficulty in potency measurements is that the storage and drying conditions of the plant, and how the cannabis material is extracted, can change the cannabinoid profile. Heat and sun exposure can cause the interchange between cannabinoids. For example, if exposed to heat or light, THCA and CBDA can be decarboxylated to D9-THC and CBD, respectively, and D9-THC can be oxidized into CBN with oxygen and light exposure. Thus, the extraction conditions, particularly temperature, should be considered with care when examining cannabinoid data. Furthermore, cannabinoid extractions have typically been done using the “hand method.” This technique is often used to extract analytes from plants and produce.

The hand method is an adaptation of the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) extraction method, which utilizes buffered salts and dispersive clean-up materials to extract pesticides from food. It is a highly manual method that requires multiple sample transfers and generates waste. Thus, ideal extraction techniques for cannabis would work around these difficulties found with making potency measurements but would be less manual and tedious than QuEChERS extractions.

The EDGE utilizes pressure and heat in a sequential system to quickly extract analytes of interest from a variety of matrices, including cannabis. The EDGE uses a two-piece open sample vessel called a Q-Cup® to hold samples for extraction. During an extraction, solvent is added to the sample in the Q-Cup, and the sample and solvent are pressurized and heated to the selected temperature for a programmed time period. When the extraction is finished, the extract passes through the bottom of the Q-Cup through the Q-Disc® filter and moves through the fluidic pathway of the system, including a cooling coil, to be dispensed into the collection vial. The final extraction volume is at room temperature, filtered, and ready for analysis. Although the EDGE does not require the use of sorbents or clean-up material, the Q-Cup technology offered by the EDGE allows for the incorporation of these materials, if needed.