Re-testing 8 Strains from Dispensaries
Our team is bringing more flower straight from local dispensaries back to our lab to validate our own precision and accuracy. The eight strains have a wide range of harvest dates, original test dates, and THC percentages, and they came to market by way of seven different testing labs.
It’s not so much a matter of whether our results will differ — we know they will to some extent. It’s a matter of how much difference we see between the original and new results. Every lab has measures in place to control for accuracy and precision (more on accuracy and precision here), but in this budding industry, there is no uniform standard implemented on the state level.
We tested each strain three times to confirm precision and ensure a minimal relative standard deviation (RSD). The OLCC mandates less than 10% RSD, and our highest came in at just over 2%.
The results are as follows, in order of the harvest date and original test date:
| Strain | Harvest Date | Original Test Date | Lab Name | Original THC % | Pree Average THC % | RPD% from Original | RSD% of 3 Pree tests |
| Treetop Double D’s | 11/2/20 | 6/23/21 | SC Labs | 28.64 | 20.12 | 35.06 | 0.80 |
| Rent Money | 7/9/21 | 7/21/21 | Rose City | 23.8 | 15.20 | 44.40 | 1.14 |
| Lemon Meringue | 11/1/21 | 11/21/21 | Reference Labs | 23.41 | 21.66 | 7.63 | 0.26 |
| Orange Cake Pop | 2/21/22 | 3/21/22 | Reference Labs | 25.28 | 22.64 | 11.37 | 1.37 |
| The Beavs | 6/28/22 | 7/13/22 | Diebel Bioscience | 24.82 | 19.14 | 25.84 | 0.72 |
| Rogue High MAC | 7/26/22 | 10/10/22 | 3B Analytical | 16.98 | 16.29 | 3.95 | 0.99 |
| Purple Dank Breath | 8/11/22 | 8/24/22 | Juniper Labs | 21.13 | 16.27 | 26.04 | 1.13 |
| Sugar Black Rose | 11/7/22 | 12/5/22 | Green Leaf | 36.4 | 19.65 | 59.71 | 2.01 |
For the oldest harvests, we’d expect to see more THC degradation, hence the higher relative percent difference (RPD) for the strains that originally came through a lab back in mid-2021. And even for the newer product, the gaps in THC percentage don’t necessarily suggest a “correct” or “incorrect” result from different labs.
There are many factors that can contribute to variance within a single harvest. The sampling process alone, which follows state regulations, can produce a sample of flower for lab testing that is ultimately very different from what ends up in dispensaries. That’s not to mention other elements like storage, air contact, or exposure to light, to name a few.
We’ll be covering more on sampling in an upcoming post — you’ll see how a massive harvest is whittled down to a small vial for testing. Stay tuned!
