The Farm Bill of 2018 has opened a lot of doors in the cannabis industry. The effects are prominent in selection of cannabinoid containing products offered on the market. One such product that is gaining popularity in the industry are CBD infused drinks. These beverages present a unique challenge compared to other matrices because of the way they are formulated. Cannabinoids are chemically hydrophobic so getting them into a drink is like trying to mix oil and water- literally. The key to enhancing the solubility and stability of cannabinoids in an aqueous solution is through the use of surfactants, or emulsifiers, in addition to a carrier oil. The emulsifier can help reduce the interfacial tension between the oil and water and help stabilize the nanoemulsion.
Now that we have some background, how would one go about analyzing cannabinoids contained within an emulsion? Let’s say we want to quantify how much CBD is in one of these infused beverages. This can be a challenging ask from an analytical standpoint, especially if some of the ingredients are proprietary. Ideally, one would like to have access to the nanoemulsion (final product) and the base beverage to assess the overall performance of a method, but this isn’t always possible.
We did some sample preparation experiments on two different locally available CBD infused beverages, with and without carbonation, to determine the feasibility of quantifying CBD in these types of matrices. The non-carbonated sample had a label claim of 10 mg of "hemp extract" per bottle, but the product was available at a discount and stored in a clear bottle so my expectations for detecting CBD were low. The carbonated sample was stored in a can and advertised 25 mg of CBD per bottle. Each of the two samples was tested by different sample prep methods. Before any of the samples were prepared the carbonated beverage was sonicated for 30 minutes to remove the CO2 from the sample. The first sample preparation procedure was a liquid-liquid extraction. This was performed by taking 10 mL of the sample and adding 10 mL of hexane. The sample was shaken for 1 min. and then centrifuged for 10 mins. A 1 mL aliquot was taken and the solvent dried off with a gentle stream of nitrogen. The sample was then reconstituted with 25/75 water/acetonitrile and injected onto an LC-PDA instrument using these instrument conditions https://www.restek.com/chromatogram/view/LC_GN0578. In the non-carbonated beverage, no analytes of interest were detected. In the carbonated beverage, a peak for CBD was detected which was confirmed by running a CBD standard.
The second technique used to prepare the CBD drinks was QuEChERS. A 10 mL aliquot of the drink was taken and put into a 50 mL centrifuge tube. 10 mL of acetonitrile was added to the tube followed by an AOAC slim pouch salt pack (Restek Cat.# 25851). The sample was shaken for 10 mins. and centrifuged for 10 mins. A 750 µL aliquot of the supernatant was transferred to an LC vial followed by the addition of 250 µL of water and vortexed prior to analysis. The sample was then injected onto the instrument. As observed with the previous analysis using hexane and LLE, no peak was observed in the non-carbonated infused beverage, but a CBD peak was observed in the carbonated CBD beverage which was again confirmed with a standard.
There were some interesting things to note about these two methods. The QuEChERS method measured a higher concentration of CBD in the carbonated drink while being a more diluted sample than the hexane LLE sample. QuEChERS proved to be a superior method of extraction of CBD from the beverage, but how can we determine if the method was truly successful?
How can confirmatory experiments be performed on a beverage sample with analytes like cannabinoids when propriety formulations are sometimes used? Matrix matching proves difficult due to the solubility of cannabinoids in the matrix. The ideal situation would be to obtain a sample of non-CBD containing beverage and the emulsifier used in the finished product in order to perform recovery experiments where known concentrations are spiked into the sample and matrix matched. But these materials are most likely not available and could be challenging to source. In these types of situations it is beneficial to work with the manufactures. A commercially available SRM could also assist in determining the success of the method. I’d like to open up the comment section for any questions or personal experiences with this sample matrix to get a conversation going. How do you ensure that your method achieves near exhaustive recovery?
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