Shelf Testing: 9 More Strains
With three shelf tests completed, with anywhere from 8 to 11 strains re-tested, the through line continues to be variance. This is not unique to our industry. Variance exists in the pharmaceutical, food, environmental and energy industries – even with rigorous testing and regulatory requirements in place. As in our industry, different testing methods, equipment, and analytical techniques can produce different results for the same sample.
If variance is expected, why do we shelf test? It’s more work. In our effort to advance cannabis science for the greater good, shelf testing can uncover issues with product quality, such as degradation or contamination, and empower growers and manufacturers with feedback to improve their production processes. Shelf testing results give us important feedback to help improve our own testing methods and continue to produce more accurate and consistent results.
Here are the latest results.
| Strain | Harvest Date | Original Test Date | Lab Name | Original THC % | Pree Average THC % | THC% +/- | RPD% from Original | RSD% of 3 Pree tests |
| Sister Diesel | 8/15/2022 | 9/27/2022 | Green Leaf Labs | 22.01 | 20.93 | -1.08 | 5.01 | 3.11 |
| Blank Check | 10/18/2022 | 12/7/2022 | SC Labs | 26.52 | 15.23 | -11.29 | 54.06 | 7.78 |
| Blueberry Headband | 12/29/2022 | 2/21/2023 | Reference Labs | 26.69 | 15.00 | -11.69 | 56.08 | 5.7 |
| Truffle Butter | 10/25/2022 | 11/30/2022 | Juniper Analytics | 26.73 | 20.63 | -6.1 | 25.74 | 7.58 |
| Melonade | 6/1/2022 | 7/25/2022 | Rose City Labs | 26.37 | 16.60 | -9.77 | 45.47 | 9.41 |
| Purple Kona Breath | 10/31/2022 | 11/9/2022 | ChemHistory | 21.67 | 14.80 | -6.87 | 37.67 | 6.52 |
| Killer Grape | 10/19/2021 | 3/24/2022 | PREE Labs | 22.22 | 15.03 | -7.19 | 38.58 | 2.34 |
| Blueberry Syrup | 10/23/2022 | 1/20/2023 | Deibel Biosciences | 23.80 | 17.83 | -5.97 | 28.66 | 5.09 |
| Blue Magoo | 10/3/2022 | 1/9/2023 | MW Labs | 28.40 | 17.50 | -10.9 | 47.49 | 5.97 |
Across the field of samples, we see the RPD falling between 5.01 and 56.08. That’s a wide spread. Without more information about the specific test and context in which it was performed, contributing factors might include the sample itself and changes to its composition over time, the wait time between homogenizing and grinding, equipment used and of course the people performing the test can introduce variance to the results. These results start a healthy conversation within the lab.
Shelf testing is one of the ways we continue to improve our methods and evolve with this growing industry. It’s not about being wrong or right. Rather, it’s how we do our part to establish greater consistency and accuracy in testing results, which supports increased confidence in the quality, safety and effectiveness of cannabis products being introduced to the market.
