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Visit to CMT Labs

The front desk at CMT Labs

CMT Labs is located on the east side of Denver in the industrial district, right next to the train tracks. I went in on a sunny afternoon to get a tour and check out their operation. I met with Hayley Witherell, their Director of Sales (@cmtlabs on the community), who hooked me up with some CMT merchandise: a lighter and a pouch of seeds (Forget-Me-Not flower seeds, not what you’re thinking). Hayley told me that CMT had recently merged with another testing lab, and they were in the process of opening a third location later in 2017. After I signed in and received a visitor badge, Hayley began the tour with me.

The desk is adorned with stickers from their clients

We first stopped at the prep room where samples are prepared for chromatography. Samples are homogenized, the cannabinoids are extracted and the final solution is diluted for final analysis. Certain samples, such as edibles and topicals, require special proprietary techniques in order to thoroughly extract cannabinoids. In several cases, samples have such a unique composition that CMT has developed extraction methods just for that matrix.

Liquid chromatography machine for measuring THC and cannabinoids

We then stopped in the gas and liquid chromatography room (HPLC/GC-FID). Because THC and the cannabinoids are complex organic molecules, the heat from a gas chromatography machine will denature them. Therefore most testing facilities rely upon liquid chromatography. There were several Agilent chromatograph machines in a row against the wall. Each machine tray holds around 100 sample vials and two tray runs can be completed in one day. As a result CMT has a quick turnaround on testing. CMT currently tests for 5 cannabinoids: THC, THCa, CBD, CBDa and CBN. They are in the process of increasing their testing capabilities to 12 different cannabinoids and will add more as new cannabinoids are discovered and their profiles added to the chromatography software.

Close up of the loading tray for the prepared samples

On the other side of the room, the gas chromatographs were set up. They are most commonly used to test for residual solvents in concentrates, such as butane, heptane, benzene, toluene, hexane and xylenes. They’re also used to test for terpene profiles, since terpenes can tolerate the heat from the gas process. CMT tests for 21 terpenes and terpenoids using a quantitative method. All of the testing machines are regularly calibrated to ensure test accuracy.

Gas chromatography for testing terpenes and contaminants

The final testing room is located on the other side of the building to prevent cross-contamination; this room is used for testing for mold, yeast and bacteria (Salmonella and E. coli). All samples, including flower, are analyzed for total yeast and mold using 3M Petri Film plates. The presence of bacterial contaminants is determined by qPCR, which monitors the amplification of a targeted DNA molecule in real-time. CMT grows their own contaminant species to use as a baseline for their tests. Every four weeks, CMT runs their known samples through the testing procedure to make sure their instruments are accurate. The scientist who runs the contamination lab told me that fewer than 5% of samples fail testing. When a failure occurs, the original batch has to be destroyed or converted into concentrates rather than go to market as flower.

CMT labs has a reputation as one of the most accurate testing labs in the state. They prefer to focus on quality and customer success, rather than be the Walmart of cannabis testing. To keep their Colorado state certification, they are subject to yearly inspections and audits of their testing protocols to make sure that their procedures are accurate and safe.

CMT Labs always has one eye on the clock to make sure your testing is done on time

As part of the testing process, CMT reviews their clients operating procedures to help them avoid contamination and get the best results. For example, one of their clients was having trouble with keeping a consistent dosage in their edibles. CMT experts observed the client’s methodology and noticed that the pipette used to add THC oil was having clogging issues. On one dose, the pipette would not fully empty, giving only half of the normal volume of oil, while the next dose would include the leftover oil from the first dose. The client needed a fresh set of experienced eyes to figure out the problem and come up with a solution.

According to CMT, the general public is unaware of the importance of lab testing, but they’re hoping that could change in the future. One thing I learned from the folks at CMT was that Colorado does not mandate any testing for the medicinal market other than flower potency. Since the regulations for medicinal pre-date the recreational regulations, they don’t yet have the same testing requirements for contaminants. Ironically you’re currently safer purchasing recreational cannabis products as they have more thorough testing requirements in place. Along with bringing the medicinal requirements up to snuff, Colorado is planning on adding pesticide residue testing to their requirements. CMT has equipment standing by ready to implement those tests as soon as the MED begins enforcement of the pesticide testing regulations.

My take home swag

A big thank you to Hayley and the staff for giving me such a thorough tour. Everyone I met was friendly and welcoming and loved talking about their work. I left better-educated about what goes into the process of making sure the cannabis I purchase is safe and effective.


Thanks for visiting, Nick!

And what a great write-up! We love it.

You’re welcome back any time. :slight_smile:


Nice interview with the Lab Director at CMT, from their blog:


Thanks for the link! :slight_smile:

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