CHOOSING THE RIGHT CANNABIS TESTING METHODS - WHY IT MATTERS

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A perfect analytical method should be accurate, robust, low cost and should not be time consuming. Unfortunately, cost and time are typically inversely proportional to accuracy and robustness, therefore the purpose of the test has to be taken into consideration when choosing the appropriate technique to use.

Quality control (QC) testing has to be performed with the most advanced tools available as these results impact batches that will be consumed and strictly regulated by agencies.  These techniques usually require special conditions (i.e. temperature, humidity, solvents, gases, vibrations, etc.), highly trained workforce and are costly. R&D testing and/or field testing, on the other hand, might be executed with less accurate, less expensive and less time-consuming procedures, since results will be used for investigational purposes and do not need to comply with any guideline put in place by regulators.

Chromatography

Chromatography (liquid or gas) coupled with different detectors is typically the chosen technique for Cannabinoid QC release testing. Accuracy, precision and robustness of chromatographic methods are greater when compared to other available options, especially because it uses daily external calibration and, in general, are more specific and sensitive.

The purchase price of a chromatographic system can vary depending on make, model, features, detector and whether the equipment is new or used; however,$40,000 is generally the opening price point. On top of the equipment price there is the maintenance cost, which is high and requires a specialized workforce. A service contract can cost up to $10,000 yearly and replacement parts are costly. Pure solvents, gases and standards, in addition to skilled staff also add to the cost per analysis. All these costs make chromatography expensive for in house use and why third-party Labs can charge $200 – 250 per sample when testing cannabis samples.

A simple chromatography machine costs at least $40,000 and it has the technician, consumable and maintenance cost. Chromatographic methods are very accurate but expensive and time consuming.

Chromatographic methods usually require complex sample preparation; extraction using organic solvents is commonly applied and can take up to 10-15min per sample. The analysis runtime can vary depending on the quality of the developed method; however, 15-25min is a reasonable generalization. Finally, the processing time also adds to the total analysis time and can take 5-15min depending on the experience of the analyst. Considering all these factors, it is fair to say that a chromatographic analysis can take ~30min-55min per sample.

Spectroscopy, UV-Vis and NIR

Sample preparations for Spectroscopy methods are typically quicker and simpler. Cannabis oil might be analyzed directly in diluted resins and grinded dried flower. Therefore, turn around is usually fast once the method is established. However, Chemometric models have to be developed previously, which takes time and if purchased separately are costly.

Spectroscopy equipment purchase price is usually cheaper than chromatography, summed with software package it can cost up to CAD$25,000. It is valid to mention that spectroscopy does not use external standard for quantification; Principal Component Regression is determined by using standardize samples and then applied to analyze the tested sample. Standardization is usually performed by using chromatography and can require a large number of samples; in this case the more is the better.

A spectroscopy machine can cost up to $25,000. Despite their strength in other fields, spectroscopic methods have proven to be inaccurate for cannabis analysis.

Electrochemical methods

Electrochemistry is another available tool available and is known to be reliable, quick and financially attractive. The numerous types of existing electrodes available make this technique specific and sensitive enough to be applied routinely. External standards are used for the quantification of samples, giving the method reasonable accuracy, precision and robustness. Commercial devices usually use calibration curves built in the software making the analysis time quicker. Sample preparation is similar to the one applied in chromatographic methods; typically, extraction with organic solvent is applied.

The low cost of electrochemical devices and the simplicity of the measurement make them ideal for analysis in the field and for R&D. Typically an electrochemical setup specifically designed for cannabis analysis is around $450 to $650. The electrodes used in each test will cost around $29 to $39, making the electrochemical methods one of the most affordable techniques while maintaining the desired accuracy in test results.

Electrochemical techniques are very economical. The instruments usually cost not higher than $700 and they need minimal consumables. Their accuracy and analysis time and mostly portability makes them suitable for R&D tests.

Cost vs. Time vs. Accuracy - What test method should you choose?

The table below summarizes the pros and cons of each technique in respect to quantitation of cannabinoids in cannabis.

 At the end, depending on the main goal of the analysis, there are different tools available. Based on the market data and how the cannabis tests are used (batch release or R&D) you can choose the right method.

If you want to release a batch and have a certification on the sold products, send your samples to a certified lab that used chromatographic methods.

If you want to do R&D tests that need to be quick, methods based on electrochemistry seem to be the sweet spot considering both cost and time.

Want to release a batch and need certificate of analysis (COA)? Use a lab that does chromatography.

Need to have quick R&D tests done? Use electrochemical tests in-house.

Selective Lab CannabiMeter(TM) is the right choice for in-house potency testing. It is also connected to Selective Lab's Laboratory Information Management System, SelectiveLIMS(TM), which immediately updates the test results in the cloud accessible to everyone in an organization from anywhere.