The growing number of cannabis products on the market can be overwhelming. Not only can it be difficult to know which vaporizer pen to get, which edible won’t get you too high, or which topical salve will be best for your back ache, but it can also be hard to tell what the cannabinoid levels are in each product — and how the levels of those chemical compounds will bring you the effects you want.
The cannabinoid profile of a cannabis strain or product, such as the ratio of the psychoactive THC (tetrahydrocannabinol) to the non-psychotropic CBD (cannabidiol), dictates how a product might influence the consumer. While each person reacts to cannabis differently, the first step to understanding a product’s potential effect is knowing how much THC, CBD, and other cannabinoids it has.
A group of researchers from the British Columbia Institute of Technology have developed what they call an improved method of testing cannabinoid levels in cannabis products. In a research paper titled “Leaner and greener analysis of cannabinoids” published last week, authors Elizabeth Mudge, Susan Murch, and Paula Brown, say their goal was to find a more accurate method for analyzing cannabinoids in raw cannabis and finished products, using more efficient techniques and fewer toxic solvents.
“We adopted green extraction solvents and a faster analysis to reduce the environmental impact of chemical testing,” Brown tells Jane Street. Using cannabis flowers from different licensed producers across Canada, she says the group’s extraction method was optimized from traditional techniques, with the goal of using not only greener solvents, but fewer solvents to increase efficiency.
The cannabis plant has more than 100 cannabinoids, which are occur in mostly acidic form in the plant’s trichomes — minuscule, crystalline hairs that cover the bud. Other cannabinoids occur while the bud is being dried or stored, or when it’s smoked and decarboxylates (when carbon is released).
According to the research paper, methanol/chloroform is the most commonly used solvent for extraction and cannabinoid analysis. The paper explains that while chronic exposure to chloroform is linked with liver and kidney damage, there’s been a push to use greener, less toxic, non-chlorinated solvents.
Lab scientists nowadays try to steer clear of chloroform, instead utilizing other common solvents like ethanol, acetone, or acetonitrile, says Dave Eagerton, vice president of lab testing services at CW Analytical. In most testing, the cannabinoids are extracted from solid material into a solvent, he explains. “Certainly all solvents can have some level of toxicity,” he says. “Every lab should be practicing good laboratory practices, using personal protective equipment such as lab coats, gloves, and goggles to protect from the kind of harm that might come from these solvents.”
Brown says there have also been issues around consistency in lab testing. “Our goal in undertaking this rigorous method validation, paying the publishers open access fees and including a Standard Operating Procedure as supplemental information was to allow contract labs and producers to easily access and adopt the method.” Having the group’s method adopted would improve consistency and transparency while reducing environmental impact, she added.
The researchers’ HPLC-DAD method not only uses greener solvents but reduces extraction time for cannabis testing in laboratories. HPLC-DAD, or High-Performance Liquid Chromatography with Diode-Array Detection, eliminates the need for chloroform while separating compounds based on their molecular structure — hence making the analysis possible.
Brown and her colleagues say their method can be used in a variety of settings from clinical studies, research, quality control, and regulatory evaluation in the cannabis industry. While most jurisdictions require known quantities for only THC and CBD, improving testing methodology will make it easier to detect information about the plant and its other cannabinoids going forward.
“Our ultimate goal is to improve the consistency between labs for cannabinoid testing to support consumers in making informed choices about the products they use,” Brown says. “Hopefully by making the method public, we can start to implement official methods and laboratory proficiency in testing to determine where the variances are happening and provide companies and consumers with more reliable testing.”