Improving the State of Cannabis Analytical Testing

Published on: 

An interview with Susan Audino

Analytical testing of cannabis involves many challenges, both technical and regulatory. As the cannabis industry slowly evolves from an illegal industry to a regulated field, many suppliers, providers, and even state legislators face a steep learning curve about what types of analytical testing are needed, how those tests should be performed, and how the performance of analytical laboratories should be demonstrated. In this content, a number of analytical scientists and standards-setting organizations are bringing their expertise to this field, seeking to educate the community and improve the overall standard of testing. Susan Audino, a chemistry laboratory consultant at Audino & Associates LLC, is one of those working in this area, and she spoke to us about the current state of testing and efforts to improve it.

How would you characterize the current state of analytical testing in the medical cannabis industry?

The state of analytical testing in the cannabis sector as a whole is tenuous at best. Where some laboratories are operating with exceptional attention to appropriate methodology and method validation, other laboratories are using instruments or methodologies (or both) that may not be appropriate for the job. Due to the lack of consensus methods, a single cannabis sample can be aliquoted, sent to three or more laboratories for the same tests, and end up with three or more very different results; all may be “right” and all may be “wrong,” but we simply can’t compare or independently evaluate them.

Cannabis testing typically includes the analysis of contaminants, mycotoxins, and heavy metals, microbiological analysis, potency testing, and solvent residue analysis. What are the main analytical techniques used in each of these tests?

Overall, the technologies used to test cannabis are no different than those used for other agricultural products and commodities. I would expect to see high performance liquid chromatography (HPLC), ultrahigh-pressure liquid chromatography (UHPLC), gas chromatography with flame ionization detection (GC–FID), headspace GC, and inductively coupled plasma (ICP) approaches used in cannabis testing laboratories. Quick qualitative checks often use lateral flow or enzyme-linked immunosorbent assay (ELISA ) tests, where positive hits are confirmed by moretraditional methods.

As the cannabis industry becomes more lucrative, interested parties desire testing that requires minimal sample material, a rapid turnaround time, and an exhaustive test report. From this perspective, near-infrared (NIR) spectroscopy is a hugely interesting possibility because it requires a small amount of sample material, does not destroy the sample so there is no sample preparation, and provides nearly immediate results. But, NIR is likely not going to provide the same results as one would obtain by HPLC, for example. Similarly, there are sources of error in determining both acid and neutral compounds via GC, as GC will decarboxylate and yield the neutrals. Although all instruments have a place in the world of cannabis analysis, we need to be sure they are being used correctly by trained personnel and in a manner consistent with the questions of interest.

What are the greatest challenges for analysts in cannabis testing?

At the present time, there are two major challenges for analysts. One is pesticides, the other is matrix. Pesticides are a challenge because there are no established tolerances or exposure limits for pesticides on cannabis plants or in cannabis products. A complicating factor is the cannabis mode of entry; for example, pesticides can be inhaled, taken orally, or transdermally. Because cannabis remains a Schedule I drug and is federally prohibited, there is no support from federal agencies to evaluate the effects of pesticides via any of these modalities. Matrix complications arise from several sources in the heterogeneity of the plant itself. In viscous gelatinous matrices such as gummy bears, extracting the analytes of interest is often challenging.

Analysts are confronted with a host of challenges that begin with receiving an inadequate amount of material. Even when appropriate quantities are provided, there are no assurances about the homogeneity or sampling protocol from which the samples were derived. Sample size is a huge issue. I’ve heard of several laboratories that have received 5 g or less of sample for extensive testing-combined with the sample’s unknown source, the small amount of sample puts a laboratory in a very difficult position to provide adequate testing.

How is the federal prohibition of cannabis affecting cannabis testing?

From the laboratory perspective, interlaboratory comparisons are difficult if at all possible, beyond state lines. As we know, chemistry (especially in the food industry) relies on solid proficiency testing, which is simply not possible in the cannabis industry. The best opportunity the industry has to evaluate proficiency is by purchasing one or a series of interlaboratory comparison (ILC) tests that are essentially dilute-and-shoot in nature. For the potency test, laboratories receive sealed ampoules of a 1000-μg/mL five-part mix in methanol, test the sample using their own methodology, and, after submitting results, receive a detailed report of their proficiency with respect to their own recovery of the known concentrations as well as comparison to other participating laboratories.

Additionally, the federal prohibition limits many Drug Enforcement Administration (DEA )-licensed laboratories from entering the cannabis-testing sector because the owners of these labs fear they will lose their licenses once they bring cannabis into their scope of work.

Finally, the federal prohibition continues to stymie both federal and private institutions that would ordinarily research and evaluate materials such as cannabis. Federally, cannabis users and patients do not benefit from Food and Drug Administration (FDA), U.S. Department of Agriculture (USDA), or Environmental Protection Agency (EPA) assurances that are afforded to other medicines and commodities.

What bodies, if any, are currently regulating cannabis testing and cannabis testing laboratories?
There is no federal oversight of any cannabis business, including testing. States are tasked with full responsibility to develop, implement, and oversee their unique set of regulations. Some states look to others for guidance, particularly in areas in which they have been less successful. The biggest challenge is that states do not always have the educational background, and especially do not have federal guidance, to help them. There have been instances in which state regulatory bodies have been influenced by persons or organizations with their own agendas that put patients and other users at a disadvantage.


How is ISO/IEC 17025 applicable to the cannabis industry?

ISO/IEC 17025 represents an international agreement established in the international accreditation community to ensure the competence of testing laboratories. The standard defines the requirements for a laboratory to establish and to demonstrate competence that is then evaluated by an objective third party. There are many benefits of accreditation, particularly for cannabis testing laboratories. For example, it provides objective attestation of competence, ensures an effective and operational quality management system, and ensures the quality system is constantly reviewed and improved upon. Accreditation also provides certain assurances to regulatory bodies that these laboratories operate under rigorous requirements and expectations that are monitored by reputable accreditation bodies. In the cannabis-testing world, these benefits are profound for the respective state regulatory bodies as well as for consumers.

Obtaining ISO accreditation is a very rigorous process that requires a fairly significant investment of resources, even for established, well run analytical laboratories. Is ISO accreditation important for such laboratories if they want to get into cannabis testing?

ISO 17025 accreditation ensures the cannabis testing laboratory adheres to and incorporates competent practices. Accreditation offers consumers the confidence in knowing testing is implemented under reliable, validated, and competent methodologies, yielding confident and reliable test results. With this assurance, consumers and regulators are in a position to evaluate the veracity of statements made on products and in test reports. Inadequate testing is worse than no testing and accreditation provides some degree of assurance of quality measures.

Many state regulations cite the monograph for quantitation of THC listed in the American Herbal Pharmacopeia (1). What are the limitations of that monograph?

In my opinion, the contributors to the monograph are to be applauded. They saw a need for testing and assembled a summary of methods that would yield= results at a time when no guidance was available and sources for methods remained quiet. As it stands, the monograph does have certain limitations, particularly as testing becomes more necessary and more scrutinized from regulatory bodies. For example, more advanced instrumentation is available than what is cited in the monograph and more validation statistics are available.

Currently, there are no standardized or consensus methods for cannabis testing. What efforts are being put forward to develop standardized or consensus methods that can be validated?

With or without standardized or consensus methods, laboratories can and should validate their own methods. There are several validation protocols available that laboratory personnel should access and implement. In fact, method validations comprise one aspect to determining technical competence in the accreditation assessment.

In the meantime, individual laboratories, instrument manufacturers, and scientific communities are endeavoring to develop consensus-based methods. For example, AOAC International and AOCS have developed working groups to focus efforts on cannabis-centric methodologies that will be put through the scientific rigors of multilaboratory evaluation, statistical evaluation, and so forth that all standardized methods endure. After the methods are vetted and approved by the scientific community, they will be enormously beneficial to the cannabis industry because they will provide scope, applicability, and specific parameters of appropriate methods.

You are chairing the first AOAC advisory panel for cannabis. What will be the primary goals of the panel in the short and long term?

The AOAC is an internationally renowned nonprofit organization that was founded on principles of good science. It is a delight to be chairing the organization’s first cannabis advisory panel. Our official “launch” date is September 2016 during the annual meeting in Dallas, Texas. We will be working with the Stakeholder Panel on Strategic Food Analytical Methods to identify at least one or more working groups that will initially focus on establishing the Standard Method Performance Requirements to develop official cannabis-centric test methods. Although the analytical field is very large, our initial objective will be to identify and address the more critical areas and then plot a course to address additional analytical needs. As soon as enough momentum and funds are available, it is my hope that AOAC will have a Stakeholder Panel for Cannabis. While ambitious, I believe it is possible.

Susan Audino obtained her PhD in Chemistry with an analytical chemistry major, and physical chemistry and biochemistry minor areas. She was the recipient of an NSF Chemometric Graduate Fellowship and was a visiting scientist at NIST, where she completed her graduate research. She currently owns and operates a consulting firm servicing chemical and biological laboratories, is an A2LA Lead Assessor and Instructor, and serves as a Board Member for the Center for Research on Environmental Medicine in Maryland. She has been studying the chemistry and applications of cannabinoids and provides scientific and technical guidance to medical marijuana dispensaries, testing laboratories, medical personnel, and regulatory agencies. Her interest most directly involves cannabis consumer safety and protection, and promotes active research toward the development of Official Test methods specifically for the cannabis industry. In addition to serving on Expert Review Panels, she is also chairing the first Cannabis Advisory Panel and working group with AOAC International.


This article was originally published in "Advancing The Science of Medical Cannabis," e-book for LCGC in September 2016. The full e-book is available for download here:


  1. Cannabis Influorescence Therapeutic Compendium (American Herbal Pharmacopoeia, Scotts Valley, California, 2013).