By Randy Robinson
You know you’re part of the cannabis community when you start thinking about your herbs in terms of THC potency. And if you’re like most patients, you probably want that number above the 20% range. THC content of a plant is usually determined by liquid chromatography. This is an analytical technique where the plant sample is ground up, mixed with a solvent that extracts the cannabinoids from the grounds, then gets filtered. The filtered mixture is mostly liquid with some cannabis oil dissolved into it. This mixture is injected into a liquid chromatography instrument that uses pressure to push the mixture along a “column”, which temporarily traps and analyzes the compounds in the sample. Usually this is done with a beam of light that absorbs at the particular frequency of the compound in question which, in our case, is THC.
In other words, the THC percentage measures the percentage of THC in the liquid mixture sample. There is an easy way to figure out how much THC was in the original plant sample, however. Using some math and some back-calculations, the THC percentage can be converted into another measurement, milligrams per gram (mg/g). This measurement compares the milligrams of THC contained with a gram of the liquid sample. This can roughly be translated to the percent of THC in the plant sample. Heather Despres, the lab director at “CannLabs”, one of Colorado’s largest cannabis testing labs, explained the conversion to Kurple: You take the THC percentage and multiply it by 10. In other words, if we take a liquid sample at 20 percent THC and multiply it by 10, we get 200 mg of THC per gram of sample. Simple enough, yeah? Not really.
The Numbers Game Despres explained that THC content is never consistent within the same plant. Typically, THC is concentrated in bottom-most buds of the plant. That means some buds will contain more THC than others, but more often than not, samples aren’t taken from the entire plant. Nor are multiple samples taken from multiple plants within a batch, which could be averaged together to give a more balanced percentage. “The results that we report are only based off of the sample we receive,” Despres said. “So if the bud has 26% THC acid, it’s just for that bud we received. Whether or not that’s relative to the entire plant that’s harvested, we would need a bigger sample. But people want to sell it, so they only want to give us the minimum amount required for testing.” The process isn’t perfect, and as of right now, recreational outlets own the monopoly over their THC data. Colorado law prevents private individuals – namely patients – from having their medicine tested at top-notch facilities such as CannLabs. “Because of the regulations, we can only accept samples from a licensed facility,” noted Despres. And although there’s officially a system for recreational businesses for sending off samples to test after each harvest, there are tricks to skew those numbers in the business’s favor. Tricks of the Trade But just how many dispensaries are skewing their numbers? We don’t know, and there isn’t a wide-reaching regulatory mechanism in place to double-check test results outside of the labs themselves. Rola, which is not his real name, is a compliance officer at a medical dispensary. He confirmed many of the rumors concerning inaccurate THC percentages being reported intentionally by some businesses. “You’re going to pick the best looking plant out of that whole batch,” he said. “You have one good plant, have that tested, and the rest could be garbage. And the consumer has no way of knowing.” Patients will just have to trust their dispensaries at the moment, or they can learn to trust themselves. Rola noted there are some easy ways to differentiate high quality product from bunk buds. He recommends that patients invest in a jeweler’s glass or some other fine magnifier. “First, look at the trim job. A good trim will preserve the trichome coverage,” he said. Trichomes should also have a milky consistency rather than appearing as clear glands.
More advice from Rola: 1. Ask the dispensary if they hand trim or use a machine; hand trimming tends to keep the trichomes intact. 2. Go for the bigger buds. 3. Avoid pre-weighed or pre-packaged flowers. Buy flower from dispensaries that weigh out their buds right in front of you.
Solutions in the Works Paul Lembeck, a botanist who used to test buds, believes it’s easy to improve the system. He suggests a more detailed method of analyzing buds and reporting THC content. “There should be a sampling procedure within the plant, from the top to the bottom,” More advice from Rola: 1. Ask the dispensary if they hand trim or use a machine; hand trimming tends to keep the trichomes intact. 2. Go for the bigger buds. 3. Avoid pre-weighed or pre-packaged flowers. Buy flower from dispensaries that weigh out their buds right in front of you.
he said. “From each branch, there should be standardization for where on the plant you test. For example, ‘This comes from the third branch, this comes from the second branch.'” He also insisted testing should stick with a single instrument such as UPLC, rather than the current mishmash of methods that can include everything from gas chromatography to mass spectrometry – all of which are reliable, proven methods for measuring cannabinoids, but can produce slightly different numbers depending on the technique and preparation method.
Despres’ suggestion agreed with Lembeck’s, in that there should be multiple sampling over a single plant or even multiple plants. However, most recreational outlets expect speed on top of accuracy, and since the state has a limited number of labs, this kind of detailed analysis may not be efficient at the moment.
There are more complications. Colorado currently only requires testing for recreational cannabis; the state currently doesn’t require testing for medical cannabis, which is ironic considering medical cannabis is sold to those most in need of safe and reliable product. Despres explained this discrepancy as a matter of foresight – or, rather, a lack thereof on the part of Colorado’s legislature. She noted that Colorado’s medical cannabis bill passed in 2000 without any requirements for testing, but that it expired this July. She said the new bill pushed through the House will require testing for the state’s medical products, which will begin in July of 2017.
Of course, patients don’t have to rely on hunches or possibly cherry-picked lab results. There are some options available to patients who may want to know if they’ve got a specific cannabinoid in their nugs, namely CBD. Bryson Rast, the lab director at Evolab, said, “The industry’s gotten to the point where they’re bringing in outside experts.” For him, the THC content reports aren’t as important as the overall confusion over how to test in the first place. “The bigger issue right now with testing is accuracy of the numbers, because there’s no regulatory oversight, there are no standard methods. But there’s a big push right now from industry for more and more accuracy.”
For patients at home, Rast recommends purchasing a home testing kit such as “Alpha- CAT”. These are thin-layer chromatography (TLC) kits that present colored spots to indicate the presence and relative amounts of cannabinoids. “It’s not really a quantitative technique,” Rast said, “but it can tell you if this is a sample with a lot of CBD or this is a bud with a lot of THC. It gives a rough ‘yes’ or ‘no’ answer.”
Patients, however, shouldn’t have to rely on home kits to verify the potency of their meds. In a perfect world, this data would be as readily available as the nutrition facts on the back of a food package. Cannabis’ legal status both federally and between states prevents a true standardization from taking hold. Some labs, such as “Steep Hill”, are trying to change that, but until cannabis is federally approved, these standardizations may have to fall entirely on states and local regulatory agencies.
“It probably won’t really happen until it goes fully federally legal,” Rast concluded. “And it’ll probably fall under the FDA. For now, it’ll probably fall on the state level for health inspections or food inspections to ensure quality product.”
Even growers within the dispensary networks want more oversight over testing procedures. Rola said he’d prefer if a federal agency such as the FDA took over testing requirements, but said for now it falls on the state’s Marijuana Enforcement Division (MED), the agency responsible for enforcing the state’s regulations on businesses and growers.
“MED should be concerned about people’s health,” Rola said, “but instead they’re only concerned with bureaucratic issues. They want to measure walls and doorways, but they don’t want to deal with the medicine itself.”
