Explaining Cannabis Lab Test Results

The New Mexico Cannabis Program has finally adopted their rule that all cannabis products must have the lab test results for potency, microbials and fungals printed on cannabis product labels. This is good rule for many reasons. Patients need to know product potency and that their medicine is safe, but cannabinoid potency is what this post is about.

testing cannabisOne of the newest NM Medical Cannabis Program Licensees recently opened their dispensary doors and the test results on the labels of their buds has created a little confusion that I plan to clear up, just because it’s good stuff to know. The labels are created from the results of a cannabinoid test called High Performance Liquid Chromatography, or HPLC for short. This method is also called High Pressure Liquid Chromatography. Both names are correct.

In the case of the most common cannabinoids, for instance THC, since the HPLC process doesn’t heat the product during testing, you easily get the results of both THCa (the acid form) as well as delta 9 THC (the neutral form). This applies to other common cannabinoids as well, such as CBDa and CBD.

But why do we have to do this? The molecular density of cannabinoids in their acid form is denser than in their neutral form, so a mathematical conversion must be done on the acid form before it can be added to the neutral form’s number for total cannabinoid(s) present, like this:

(THCa x .877) + ∆ 9 THC = potential THC of a product at the time it is tested.
(25% THCa x .877) + 2.5% ∆9 THC = Total THC
21.93% + 2.5% =  Total THC
24.43% = Total THC
This product sample has 24.43% THC

So why haven’t we all been seeing this on our labels from the start? It could be for a few reasons.

One: Another type of testing called Gas Chromatography, (or GC for short), may have been used. GC employs heat in the the process and this means the acid form of the cannabinoids is heated to the point of conversion to neutral, or in essence – the cannabinoids are decarboxylated and the result is just one number for each different neutralized cannabinoid.

However, the GC process can employ another step to get the numbers for the acids THCa and CBD by a method called derivatization, before the heating occurs. In cannabis testing this step stabilizes the acids, preventing their conversion to neutral form during GC’s heating process. But HPLC is a more simple process, leaving less room for error. This is my take on all the reading I did on the subject. However, this is a frequently debated subject in the cannabis testing community and I’m sure the debate will continue.

Two: Yet another type of testing called Thin Layer Chromatography, (TLC) may have been employed. As far as I know there are no labs in New Mexico using this method to test cannabinoid potency, which is good because it is the least accurate of all the processes, but it is sometimes used elsewhere.

Three: The label cannabinoid numbers may have already been converted by the testing lab before the labels were printed. Producers or dispensaries should not be able to change the numbers before the label is printed because the test results are in our Program’s seed-to-sale tracking system, and the labels should be printed directly from these results.

Four: The item may not have been tested and historical data for the strain was used instead. This should not be happening in New Mexico anymore.

My conclusion? For me HPLC is preferred over GC because it measures the cannabinoids present in their natural forms, with no heat, and with no extra steps that must also be incredibly accurate. In my case I want to know the breakdown of THCa and THC separately, being that I don’t decarboxylate all my medicine because THCa is better for chronic pain from inflammation, as indicated to me by Rev. Dr. Kymron DeCesar, (see this post). I have no way of knowing the THCa content in a product with regular GC results because the product was decarboxylated in the testing process, unless another step (derivatization), is completed accurately before the actual quantification, or final numbers.

If decarboxylated numbers are all you are looking for, then CG is just as good as HPLC which is why this the preferred method of law enforcement. No need to buy and maintain another scientific instrument to give these numbers. In a recreational market it may not matter to consumers, but as time goes on I believe HPLC will be the preferred method of testing cannabis to be used as medicine. The most accurate information available is very important to have if you are making edibles and tinctures, where the acid cannabinoids may not be fully activated until use or consumption, if at all. In my case, when making oils and tinctures I NEED to know the numbers on the raw plant matter, not the heated stuff.

cannabis tinctureAs long as I am throwing out opinion, I also believe that every cannabis testing laboratory should have both instruments. After speaking with both our labs in New Mexico I am happy to report that they have stated that they do in fact have both. What I also come away with is that GC may give the most accurate numbers for anything that will be heated during processing and consumption, and HPLC may be most accurate for cannabis products that will never be heated. But in the end, either will do. I also walk away from this wondering why anyone would purchase cannabis medicine that will never be heated before consumption without the THCa, CBDa and CBCa numbers in the test results.

What’s in YOUR medicine?

There are rigid certifications for test laboratories, but as of this writing there are no government regulations or specifics on exactly how labs test cannabis medicine.

I am not a scientist. Not even in my dreams. This report is my layman’s interpretation of the research I did and conversations I had with two cannabis testing labs in NM, one other NM PhD scientist, and a cannabis scientist/educator in California.

Other Resources:
– Cannabis Analysis: Potency Testing Identification and Quantification of THC and CBD by GC/FID and HC/MS by PerkinElmer
– Lab-Testing Cannabis: What You Need To Know – Medical Jane
– The Importance of Lab Testing Cannabis – docksidecooperative.org  docksidecannabis.com
– ChromaBLOGraphy


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