CannLabs-preferred methods, calibration standards, and how we do what we do...
Operating since early 2010, CannLabs is the premier medical cannabis testing lab in the state of Colorado. There are many reasons for this, including the fact that our method of choice is the most accepted and cited for this kind of application, we keep all instruments and equipment tightly calibrated with low tolerance ranges, and our SOPs (standard operating procedures) reflect the proper way of gathering true potency data. We are here to answer any questions you may have and have provided the information below to show you how good science means good data, happy patients, well-formulated products, and a true way of translating dosing to healthcare professionals.
Our chosen method
High Performance Liquid Chromatography (HPLC) is the most widely accepted method for the identification and quantitative measurement of the constituents of all medical plants, including that of cannabis sativa. The American Herbal Products Association (think dietary supplements and nutraceuticals), the WHO, the UN, FDA, DEA, etc all recommend HPLC in their various guidances as the only accepted quantitative method for potency analysis. The reasons for this are quite straightforward. There are no chemical modifications to the molecules (cannabinoids) in this case, and all of the plants constituents are kept in their naturally occurring forms. This allows us to obtain true data on both the acidic (e.g. THCA, CBDA) and neutral (Delta 9-THC, CBD, CBN) of the cannabinoids.
Calibration of equipment and instrumentation
We pair this HPLC methodology with the use of third-party reference standards (i.e. 99.99% pure cannabinoids from a chemical supply company such as Restek or Sigma-Aldrich). These reference standards are DEA Form 222 exempt, meaning they are at a concentration of 1mg/mL or less and supplied in a toxic solvent such as methanol so that the cannabinoids cannot be reclaimed. Before they are cleared as exempt, the DEA and FDA regulate the production of these molecules and must certify them with the help of the supply company (e.g. Restek) before they are released onto the market. Therefore, each aliquot comes with a certificate of analysis showing its purity and concentration when they arrive at our lab on dry ice. These reference standards are then logged and quarantined in our lab under proper storage conditions until further use. When calibration time comes, a fresh aliquot of each cannabinoid (or mixture thereof) is opened and diluted properly to form a linear working range or calibration curve. Our curves run from .05% to 30% and all have a minimum correlation coefficient of 0.99 (the more 9s the better! Most environmental labs require two 9s after the decimal, 1.0 would be a perfect straight line). See Figure 1 for an example curve from our last recalibration. Our tolerance range is 5%-meaning if we run a known reference standard (which we do daily) against our calibration curves and it comes back at greater or less than 5% deviated from its true value, the instrument is re-calibrated. Therefore, we always have two feet to stand on and can always provide you with reliable, accurate, and precise data.
FIGURE 1. Calibration Curve of Cannabidiol, 1 June 2012.
Having an instrument in great calibration only goes so far. One must ensure that all applicable laboratory equipment is in great working condition and calibration. For example, our pipettes (used for volumetric transfers of solvents and extractions) and scales are all calibrated and certified by a third party (SERCOM). SERCOM routinely calibrates instrumentation and equipment for academic research institutions, governmental agencies, crime labs, etc. Once a lab has every step in the process calibrated and properly maintained, real data starts flowing!
Additional methods used by other labs-pitfalls
The two other most common methods for the identification of or quantification of medical plants and their chemical constituents are GC (gas chromatography) and TLC (thin layer chromatography).
GC can be quite useful for trace analysis of cannabinoid metabolites in urine, hair, blood, etc. (i.e. drug testing) but is not particularly useful in the quantification of cannabinoids, as the molecules themselves are heated and modified during the analytical process. Much care must be taken to protect the functional groups on the acidic cannabinoids (derivitizations) during GC analysis, and NO LAB in Colorado is currently practicing this. The use of GC without derivitization provides potency numbers that are routinely 15-40% low depending on the conditions.
TLC (thin layer chromatography-a blotting technique) is especially useful for the identification of medical plants but not particularly useful for elucidating how much of a constituent is in that plant. The method relies on chromatographic paper with a color-changing reagent. The cannabinoid extract is the blotted at various volumes on the reagent paper. Depending on the concentration of the constituents present, the various blots change color and the densities of the spots are correlated with a number (hopefully but not often related to a reference standard). Because of the high variability in each of these steps, it is quite difficult to get reliable quantitative data. This is why the aforementioned agencies recommend this method for qualitative (identification) purposes and not quantitative (real numbers!) purposes.
Keep in mind that all methods have their pitfalls, but also know that here at CannLabs we use the most accepted, accurate, and precise methods for potency analysis and strive every day for perfection. If your lab is relying upon one of these other methods, be aware that the data you're receiving has a much larger error range, and poor precision and accuracy.
What we test - the preferred method applied
The versatility of our HPLC and various methods that have been developed here coupled with proper extraction methods for every type of product we see means that we can analyze it all. Some products need a bit or work to generate the proper extraction conditions, but don't be afraid to ask and bring it in!
Here's a list of commonly analyzed products:
- Cannabis: flowers, trim, sugarleaf, concentrates (bubble hash, solvent extracts, kief, oils, etc.)
- Cannabis edibles: brownies, cookies, suckers, gum, gummies, pixie sticks, drinks, pills
- Cannabis topicals: lotions, salves, lip balm, etc.
Please refer to our services page for more information.
