The Role of Independent Regulatory Cannabis Labs

Third-party cannabis testing laboratories play a crucial role in ensuring that the cannabis and hemp material that reaches the market is accurately labeled and free from dangerous contaminants.

But beyond internal method validation, how can labs be sure that their routine analysis methods are up to scratch? This is where independent regulatory labs come in. Through managing various inter-laboratory comparison tests as part of a laboratory quality assurance program, independent regulatory labs give cannabis testing labs a way to demonstrate their competencies and identify areas where their measurements could be improved.

Independent tests help third-party labs improve

Most interlaboratory comparison (ILC) tests and studies operate in a similar way. Enrolled labs receive identical verified samples for testing. The labs then submit their results to the relevant laboratory quality assurance program or proficiency tester. The results from all of the participating labs are compared, and usually some collective trends are identified and published for the industry to consider.

Such laboratory quality assurance programs are becoming a common sight within the cannabis and hemp industry. And it is probably no coincidence that this is happening at a time when lab shopping – the practice of getting products tested at multiple labs to find a more ‘desirable’ result – is being spoken about and criticized more widely.

“We’ve been hearing throughout the industry [that if] you send a sample to three or four labs or more, you might get different values from all of them,” Brent Wilson, a research chemist at the National Institute of Standards and Technology (NIST) and member of its Cannabis Laboratory Quality Assurance Program (CannaQAP), previously told Analytical Cannabis.

“So, the goal is to improve the analytical measurements that are being done in cannabis laboratories and forensic laboratories, to where we’re promoting good manufacturing practices and encouraging safe products.”

Testing laboratories are also expected to provide some evidence of proficiency as part of the ISO/IEC 17025 accreditation process, which is another reason why a lab may want to participate in a proficiency testing (PT) scheme.

Quality assurance extends beyond commercial testing labs

There is a range of different PT schemes available within the cannabis and hemp industry. For example, The Emerald Test, a PT program established by Emerald Scientific in 2014, offers cannabis labs that pass its testing program an Emerald Badge that can be displayed to prove the lab’s competency to customers.

In contrast, CannaQAP positions itself as a perpetual interlaboratory study mechanism, akin to a PT scheme but without the pass/fail grade.

“NIST’s CannaQAP study is not a proficiency test. This study is meant to help labs and the community overall improve the accuracy of their measurements,” Colleen E. Bryan Sallee, a research biologist at NIST, told Analytical Cannabis. “We encourage study participants to reach out to us to discuss their individual results and how they can improve their methods.”

NIST says that CannaQAP may benefit more than just third-party commercial testing labs. Forensic labs developing methods to differentiate hemp and cannabis, regulators using labs for market surveys, and researchers conducting clinical trials are also encouraged to participate in the CannaQAP exercises.

“NIST has no regulatory role in relation to hemp or marijuana. Our goal is to help labs achieve accurate measurements so that agencies that enforce laws and regulations can do so fairly and effectively,” Sallee continued. “This is important to law enforcement agencies concerned with controlled substances as well as regulatory authorities concerned with product and consumer safety, accurate labelling, and related issues.”

CannaQAP reveals first results from second phase

For its first exercise, the CannaQAP team sent participating labs samples of hemp oil and asked them to quantify the amount of THC and CBD present in the oils. In a report published in late 2021, the team found that the majority of labs were able to quantify these cannabinoids correctly.

The CannaQAP recently released the first two reports from its second exercise, which asked labs to test the moisture content and toxic elements present in cannabis plant materials.

In the moisture test results, the CannaQAP team found that most labs reported results significantly above the tolerance ranges established by NIST. They noted that a variety of drying methods were being used by labs, most commonly desiccator drying, vacuum oven drying, and thermogravimetric analysis. However, no method was significantly better at drying the plant samples than another.

“The variability in results highlights the need for consistent use of drying methods across the community,” Sallee said. “It also highlights the need for a reference material that includes moisture values. A hemp (not marijuana) reference material [RM] is in production at NIST. This RM will include a composite moisture value obtained from both a 30-minute oven-drying method and a desiccator drying method that yield similar results.”

Technical recommendations for laboratories

The toxic elements test primarily focused on the labs’ abilities to quantify the “Big Four” heavy metals (arsenic, cadmium, mercury, and lead) in two hemp samples and a control material provided by NIST. The determination of other toxic elements, including manganese, nickel, and uranium, was also tested.

The CannaQAP team found that participant results varied depending on the sample being tested, the analyte being tested for, and the amount of that analyte in the test sample. Most labs reported using microwave digestion as their sample preparation method and inductively coupled plasma mass spectrometry (ICP-MS) as their analytical method. While this is well suited to many toxic elements, the CannaQAP report does also note that the sensitivity of ICP-MS for mercury is low, but this can be improved through the use of additional methods.

“Laboratories must balance many factors when deciding on the best methods to use for trace element measurements,” Sallee said.

In the technical recommendations section of the report, CannaQAP does note that the measurement of very low levels of toxic elements is challenging for labs, but recommends that labs avoid reporting a zero for certain elements in their test results. Zero is not a quantity that can be measured, the report reads, stating that if values are below the limits of quantification then the results should be reported as such.

This article originally appeared in the Analytical Cannabis - March 2023 Digest.