The testing of commercially available cannabis for cannabinoid profile and potency is becoming more prevalent and is seen as increasingly more important information to have by patients and dispensaries.  The availability of cannabis testing provides valuable information to patients, promotes the availability of medically important cannabis options such as CBD-rich cannabis through identification and use in strategic breeding programs, and promotes the overall legitimization of cannabis use.

       Cannabinoid testing provides objective information used by medicinal cannabis patients for use in selecting their medicine.  The cannabinoid profile information helps the patient choose the cannabis that best suits the therapy requirements of their ailment.  The cannabinoid potency information provides guidance they can use in determining their dosage requirement through self experimentation, often called “self-titration”.  The presence of reliable information also supports the ability of the patient to achieve a repeatable experience of therapeutic benefits without experiencing unwanted intoxication.

     With an increasing awareness, and a concurrent rise in interest in consuming cannabinoids other than THC, potency testing can play an important role in promoting awareness and availability of non-THC options.  First, through the identification of cannabis and cannabis products with medically important non-THC cannabinoids such as CBD that cannot be detected by visual or other sensory means.  Secondly, through the use of testing to identify plants for use in breeding programs designed to develop and isolate cannabis that is high in CBD, CBG or some other cannabinoid of interest.  Cannabinoid testing can be used to identify the cannabinoid profile of plants to determine genetic crosses that promote the development of non-THC dominant cannabis based upon our understanding of the genetics of the expression of those cannabinoids.

     Cannabis testing has the potential to provide enhanced legitimacy to the cannabis industry on a few different levels.  One such area concerns use and consumption where cannabis testing provides information such as potency and the absence of harmful pesticides.  There is also the development of a rapidly growing body of data the cannabis laboratories generate that can be used to support the characterization of cannabis as a medicinal plant in the effort to re-schedule its federal drug classification.        

     As the prevalence of cannabis testing is on the rise a dynamic environment, driven largely by economic influences, is developing around the emerging cannabis testing industry.  In the recent past, the decision to test has largely been driven by weighing the costs and the benefits from a marketing perspective.  In the midst of a highly competitive market for medicinal cannabis sales new laboratories are emerging on a frequent basis in California and other states to serve a perceived economic opportunity.  Some activist groups have raised concerns over the nature of segments of the new industry.  The presence of non-qualified service providers, “dry labs” who outsource all analysis or fabricate results and the existence of unscrupulous instrument companies marketing equipment to collectives to perform their own testing at significant cost are raising concerns.  As a response, patients and collectives are asking important questions about the reliability of the results they are depending on and investing in.

     In the current cannabis laboratory industry there is a lack of regulatory oversight that exists in most other fee-for-service analytical chemistry industries.  It is this lack of oversight that makes the water a bit murkier when looking for a reputable and qualified service provider for cannabis testing services.  In an environment where providing analytical results is regulated such as for drinking water, soil and food, a customer can simply choose from a list of service providers who have all been certified to the same set of standards for accuracy and precision in their work.  In such a regulated environment there exists an agreed upon set of requirements for an analytical method to be considered validated through the systematic verification of the reliability and repeatability of the analytical system.  There also would exist an agreed upon set of requirements for quality control of ongoing work such as requirements for the frequency and acceptance criteria of the calibration of equipment.   In the absence of regulation these aspects of analysis, from method validation to providing results to a customer, can happen under much more widely varying circumstances. 

     The importance of the use of consistent criteria for method validation and ongoing quality control become clear when you consider the multiple factors that affect accuracy and precision in an analysis like cannabinoid testing.  The results are significantly influenced in the case of cannabinoid testing by the method of sampling at the dispensary or cultivator level.  A sample that is representative of the entire unit of material must be submitted for analysis to obtain a result that accounts for the variation in the unit of plant material.  There is also the influence of the second tier of sampling which occurs at the level of the laboratory where the sample is prepared and extracted for analysis.  This process involves the use of precision weighing and volumetric measurement equipment which must be calibrated and verified at regular intervals.  The proper calibration of analytical equipment is also imperative to the production of reliable and repeatable data.  Key factors include the use of certified standards that have been third party tested and certified for purity and concentration.  Proper maintenance of equipment is a final important element for ensuring that the results provided to the customer are delivered with the highest confidence level.  In the absence of oversight, the cooperative work between labs to perform side-by-side testing of samples can provide an important element to fostering confidence at the consumer level.

     A prominent aspect of cannabis laboratory practice that varies between service providers is the choice of analytical equipment.  In general, the choice of equipment centers on the use of gas chromatography versus liquid chromatography for cannabinoid analysis.  As in every industry there is often an effort to promote what differentiates a service as what makes it better than another.  In the case of GC versus HPLC some service providers have attempted to position their choice of equipment as superior to another.  Both types of equipment can provide accurate, reliable data for cannabinoid analysis.  It just isn’t as simple as GC versus LC.  A factor important to consider when reviewing the equipment that is appropriate for a given analysis is making sure the correct type of detector is being used, this is especially important for GC analysis of cannabinoids.  In the case of GC there are options of FID (flame ionization detector), MS (mass spectrometer) and TCD (thermal conductivity detector).  Both GC’s equipped with FID and MS detectors have been shown to provide reliable results.  The TCD detectors, commonly sold by instrument companies to dispensaries, are not a good choice.  One reason is that the results are often influenced by the interference of other cannabinoids present aside from THC, CBD and CBN. 

     There are also a segment of service providers providing results from TLC or Thin Layer Chromatography often referred to as “test strips”.  In some of these cases these test strips are promoted as being able to provide accurate potency results for cannabis.  In general, without specialized equipment, test strips are only viable for use to tell whether or not certain cannabinoids are present, but not how much is present, e.g. potency. 

     The most appropriate method for analysis is also determined by the type of sample being analyzed.  In today’s cannabis industry, the vast majority of samples submitted to laboratories for testing consist of processed, dried flower intended for vaporization or combustion.  Testing by GC-FID, GC-MS or LC is appropriate for these samples when looking to identify cannabinoid profile and potency level. For those samples that may contain the un-activated or “acid” form of THC and CBD when consumed, analysis by LC is more appropriate.  GC is unable to detect if these “acid” forms remain present, a consideration that is important when trying to consider dosage of an edible or tincture ingestible.  This is because analysis by GC essentially simulates what happens when cannabis is vaporized or combusted.  The acid forms of THC and CBD are converted to the active forms when heated. Heating is a part of analysis by GC.  This is important because many tincture and edible makers do not activate their cannabinoids through adequate heating of their products, leaving some cannabinoid in the “acid” form.  For a summary on the similarities and differences between GC and LC equipment see table 1.     

Table 1.  Comparison of Gas Chromatography and High Performance Liquid Chromatography

Gas Chromatography Liquid Chromatography
A low pressure stream of gas helps move the compounds to the detector A high pressure stream of solvent helps move the compounds to the detector
The system is heated during analysis The system is usually at ambient temperature during analysis
Detects total available THC, CBD and CBN and other activated cannabinoids Detects THC, THCA, CBD, CBDA and other acid and non acid cannabinoids
Cannot detect cannabinoid acids Can detect cannabinoid acids
Analysis does not produce significant waste Analysis produces significant solvent waste

    

     It becomes clear that in the current non-regulated environment the consumer has to be savvy and know what questions to ask a prospective cannabis lab.  A group of service providers* from various states plus an international adviser compiled a list of 10 questions to ask your cannabis scientist to act as a guide for those looking for a qualified partner.

10 Questions to ask your cannabis scientist

1. What training or expertise do you have to be able to perform cannabis analysis?

2. Which cannabinoids do you test for? Do you have reliable reference standards for all of them?

3. Describe how CBN is related to THC, and why is it important to test for it?

4. What kind of samples do you test (flowers, edibles, tincture)? Have you optimized your extraction and analysis protocol for each kind of sample?

5. What do you do with left-over samples?

6. Are you aware of acidic cannabinoids? In samples such as edibles and tincture they can be present at high levels. How do you deal with that?

7. What is your analytical methodology for testing cannabis (HPLC, GC, TLC, other)? What are the limitations of your selected method?

8. What is the average THC/CBD content your lab has measured?

9. Did your lab ever test the same cannabis twice, with very different results? What was the explanation for that, and what has been changed to prevent it from happening again?

10. Analytical methods need to be ‘validated’ before you can be sure they are fully reliable. Have you done this already, and how did you do this.  Did it include a third party?  If you didn’t do it yet, how can I be sure my results will be accurate?

*Contributors: Arno Hazekamp (Netherlands), Samantha Miller (Pure Analytics), Paula Morris (Medea Labs), Noel Palmer (Montana Botanical Analytics), Jeff Raber (The Werc Shop) and Eric Taylor (California Botanicals).  Collectively the ACS, Alliance for Cannabis Science.

 

One Response to Cannabis Testing- The Current Landscape

  1. Eliza Adams says:

    Hi, thanks for the informative article. The author wrote, ” In the case of GC there are options of FID (flame ionization detector), MS (mass spectrometer) and TCD (thermal conductivity detector). ” I would be interested to know if anyone has used a PID (photo ionization detector) for CBD/THC/CDN analysis, and how it compares to a FID detector. Thanks!

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