14 Marijuana Labs Participate in ‘Proficiency’ Test

Yet another sign that the marijuana industry is maturing: 14 cannabis labs from across the country recently participated in a test to determine THC concentrations in blind samples.

The Intra-lab Comparison and Proficiency Test was part of “an effort to help promote quality assurance in a previously unregulated and fast-growing industry,” according to a press release from Emerald Scientific, a testing equipment provider that oversaw the study.

The labs, located in five states, each tested a cannabis sample for THC concentration using their own internal methods. Several industry supply labs, a university and a state health agency also participated.

, 14 Marijuana Labs Participate in ‘Proficiency’ Test

A testing company that meets criteria established by the International Organization for Standardization (ISO) managed the process and collected the data.

Out of 19 reported results, three labs were within 1% of the true THC concentration, another 13 were within 10% of the number, and the furthest was off by 32%.

Other details – including the results of individual labs – were not released. Full results of the test will be available in January.

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8 comments on “14 Marijuana Labs Participate in ‘Proficiency’ Test
  1. Ean Seeb on

    I can’t wait to see these results! We as operators have wanted to see some type of collaboration and standardization for cannabis test labs for years now.
    We undertook our own blind testing of several test labs in Colorado and the results were off by over 30% from just 3 labs! That was back in 2012. We have seen some significant advancements in both equipment and processes but it’s still a very new industry with lots of room for improvement.
    Here’s the story from 2012 dealing with testing in both Colorado and California:

  2. Windy City on

    …as a matter of course, there needs to be a standardization for cannabis test labs, to analyze and determine the content of the cannabis being sold for the public good.
    This would be inclusive of the entire industry, from medical and recreational marijuana to industrial hemp.

    Once the Federal government gets in step with the 21st century, I am sure that this will be a standard requirement…

  3. Ken Snoke on

    This test was a start in the right direction, but the results need to be analyzed and discussed by the community and we need broader participation in the tests this spring. There are just too many factors to be discussed here, but some good conversations are starting about the results at, and the detailed results will be released and discussed at a conference in January ( There is so much to accomplish in this area, but other analytical testing industries have paved the way before us, so we don’t need to recreate the wheel. We just need to continue down this path and in a short while, dispensaries, growers, patients, and consumers will be able to expect meaningful test results that are reproducible and accurate.

  4. Jahpharmer on

    Why so long for releasing the results (…not until January)?

    IMHO smacks of politics here…if the data already shows the proficiency of each lab’s accuracy, then put a name to it too!

  5. Carl Meuser on

    Until there is agreement on the methods of analysis, there is little hope of good agreement between laboratories. The two most popular instrumental methods (gas chromatography and liquid chromatography)have inherent systematic differences.

  6. Lonnie Painter on

    Finally another so called ring test. I hope it was a blind test and the labs didn’t know the samples were part of the test. I’ve wondered why for the last couple of years why the same samples I sent to SC Labs and the Wercshop seemed to came back with SC Labs being 6 percentage points higher. For a while I was a partner in a delivery service in Orange County, Ca. We had a sample that tested at 14% THC by the Workshop I told my then partner when we sent a sample of the same pound to SC Labs it would come back 6 percentage points higher and low and behold SC Labs gave it a 19 +% THC. In 2013 I received several lbs of various strains including a CBD strain from Ringo at Sohum Seeds’ Tea House Collective that had been tested at SC Labs. When we sent samples to the Wercshop they all came back six percentage points lower. When I showed the conflicting lab reports to Ringo he refunded me well over a thousand. I’ve complained about SC Labs monopoly agreement with Weedmaps for a long time. If you want to advertise on Weedmaps that you lab test you have to use SC Labs. Dispensaries love it because a strain that is low in THC may come back several % points higher.

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