THC Ratings: Does Size Really Matter? Part 2
Published October 06, 2020

Testing for THC Percentages

The guidelines for testing in the State of California are as follows. First, a 22.7 gram sample of bud is collected from each ten pound batch. Second, the sample is received at one of the many new labs, made specifically to service the cannabis industry in CA. These labs typically are not required to adhere to GLP (Good Lab Practices) Standards. These standards require constant re-calibration of mass spectrometry machines. This includes verification tests on various machines in separate lab locations. An amalgamation of large quantities of test material to ensure homogenous samples.

Standards for testing nutrient percentages in food require grinding and mixing 1 kilo of material to homogenize the sample. Grinding up a kilo of high-quality bud for testing purposes is not economical. It is equally unlikely that all these new canna test labs are calibrating their equipment frequently or running cross verifications. So, the accuracy and reliability of these THC percentage numbers are highly suspect from the get-go. Trace quantities of banned contaminants can be accurately identified with ease from small random samples. However, reliable measure of molecular concentration percentages, like THC percent, requires large samples with fully blended materials. Even different parts of an individual bud can have widely varying THC percent. Without creating these homogeneous samples, the number cannot be an accurate reflection of the end product.

Additionally, the accuracy of the equipment and testing protocols cannot be fully trusted. We have sent a sample from a batch of Wedding Crasher that came back at 10%. Re-submitting a sample from the exact same batch to the same lab, resulted in 22% THC. With high demand for testing, it is not possible for these new canna testing labs to take the time required
for frequent machine calibration and verification. For California cannabis products, we should recognize then, the THC percent number is neither reliable nor representative.


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