Marijuana Miracles

GrowingMedicinalPharmacologyWhat is that flower really about?

August 11, 2021by Nicklous0

This is a repost from –

When my roommate’s basement XJ13 lab tested at over 24% THC potency in 2013, High Times’ “Strongest Strain on Earth” was a 27% THC Ghost Train Haze. That XJ packed a decent punch but the results still didn’t sit right with me. For only $50 dollars more an ounce, I could walk down the street and get something way stronger.

If the basement grow was really that close to maxing out THC potency, could the “entourage effect” really be what made good weed feel stronger? What were the results of cannabis potency testing really telling me?

Two years later, on one of my first visits to a recreational store in Seattle, I found a potency label that broke the laws of math and physics: 103.5% Total Cannabinoids. At first I laughed, thinking how many dabs did it take for that stroke of genius?

But I’d soon discover that printing an accurate cannabis potency test would take a lot more than fixing silly mistakes. Sure, deceptive practices were (and still are) widespread, but the industry has also faced some very new and sudden challenges that will take more time to work out, even with utmost integrity.

Let’s take a closer look at the science of marijuana potency testing!

As much as we all got used to ‘judging a bud by its cover’, most of us have also experienced the letdown of a looker that just doesn’t seem to cook right. That’s one thing that made legal weed so exciting: potency proof on every package! For markets that don’t have samples, or smells, or even let you see the product first, mandatory THC potency testing was a real no-brainer.

Unfortunately, in all the haste and hubbub, an elephant in the room went unnoticed: The science behind cannabis potency testing wasn’t ready yet. Although researchers and organizations like High Times had been analyzing THC concentrations for years, standardizing test results across a multi-billion dollar market is much different than carefully processing a small group of samples from time to time.

Creating a system where millions of test results can be compared to one another takes many years of work from experts, professionals, and agencies like the International Organization for Standardization (ISO), which certifies labs all across the world for precision and accuracy. In recent years, plenty of cannabis testing labs have obtained ISO certification, but there’s still no ISO certification for testing cannabis (due to prohibition) so it’s not actually a check on cannabis-specific techniques and methods.

To make matters trickier, there aren’t any botanical products like cannabis that have been tested on such a large scale, so there’s no universal standard operating procedures (SOPs) from which to develop standards for cannabis testing. For more on that, check out this paper in the Medical Cannabis and Cannabinoids journal, which advocates for better standards in cannabis testing because those standards will actually change how the world of science views all medicinal plants and herbs and not just cannabis – and that’s a big deal!

To get an idea of the status quo, let’s explore how that lack of standards translates into what you see on a cannabis potency label.

As it turns out, the test that read 103% total cannabinoids was actually normal and doesn’t necessarily indicate a mistake or foul play at all (assuming it’s a highly potent product, like CBD isolate). That’s because, even with everything else in order, quantitative lab tests almost always assume a tolerance for what we’ll call ‘measurement uncertainty’, which is basically how much the results could be off from the actual value.

For example, if the measurement uncertainty for a sample of 100% Pure THC is about 10% and the lab returns a result of 105%, that still falls within the expected measurement uncertainty. For more details on that, check out this article from Botanacor Laboratories about lab testing CBD. Not quite an exact science, is it?

That type of discrepancy poses a big problem for regulators, and it’s one reason the National Institute of Standards and Technology recently sent over 200 cannabis testing laboratories a set of identical samples to analyze (that’s called a ‘ring test’). The study is still underway but one of its participants sent us the preliminary report. Of the 200 or so participating labs, only 20 tested marijuana (not just hemp), and each of those 20 was sent three different samples. You can find the full preliminary report here (look for Table 2 on Page 7), but we’ve summarized the relevant data in the table below:

THC Potency Chart for NIST Ring Test

Plant Sample 2 Plant Sample 3 Plant Sample 5
Target Average 12.7% 29.2% 44.2%
Consensus Mean 14.7% 29.3% 42.0%
Minimum Result 10.0% 19.0% 26.6%
Maximum Result 23.3% 40.3% 59.0%

Basically, the three samples were expected to test at 12.7%, 29.2%, and 44.2% (the target averages) and the average of values from all 20 labs (the consensus mean) comes to within 2% for each sample. The part that’s interesting is how far off the individual results were from one another. For the 12.7% sample, labs sent back results as low as 10.0% and as high as 23.3%. Results for the 29.2% sample came back between 19.0% and 40.3%. Not surprisingly, the 44.2% sample had the widest range of results spanning from 26.6% to 59.0%.

The problem here is that even though measurement uncertainty of pure THC or CBD powder is about 10%, the uncertainty goes way up for botanical products like flowers or buds that don’t have a homogeneous consistency. If we just look at ‘Plant Sample 5’, we are seeing a measurement uncertainty of 73 percent!

So although the averages balance out pretty well, it’s not like producers are printing the average of 20 tests on a potency label – they’re printing the highest one they can afford to find. And that ability to shop around or retest products until they return the highest numbers (aka lab shopping) is a huge problem for small producers trying to compete.

But instead of sending a sample around to a dozen labs to find the right results, producers can usually save money by patronizing the ones that return those higher values – even if it incurs a higher pay-to-play price. It’s easy to say that’s unethical, but the wholesale price of weed is based on THC potency testing and the margins are razor thin as it is. If you were a producer facing acquisition, or a lab trying to retain clients, what would you do?

Since it seems clear that marijuana potency testing needs time to develop better universal standards, let’s talk about what we can do as consumers.

Maybe mandatory THC potency tests didn’t work out as well as we thought, but that doesn’t make them totally useless. Personally, unless two products are from the same brand and the difference in THC Potency is over 5%, I pay more attention to the presence of CBD, other cannabinoids, and terpenes.

If you want to do your own trialing at home, don’t forget that density matters, too. We can’t accurately compare the strength of two different products by just taking a pinch, we need to weigh out the same amount each time to account for changes in density (but even I don’t do this very often).

For me, being satisfied really starts with knowing what I want and paying attention to what gets the job done. Some strains tend to come out similar every time and others will vary significantly. When I find a great product, I take note of the breeder, the grower, and the ratio of terpenes when possible.

For consumers that still want to dive into the science and progress of cannabis potency testing, one of the best benchmarks for a cannabis testing lab is The Emerald Test. They no longer publish a list of participating labs but you can still check the 2019 participants list or inquire with your local labs. Their latest report has an overview of findings, but keep in mind this data represents the labs trying to prove their accuracy and businesses that engage in deceptive practices aren’t likely to be a part of The Emerald Test. In other words, The Emerald Test shows that doing things well is possible, but even the most ambitious labs aren’t getting it right all the time.


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