Cannabis Analysis: 7 Critical Testing Procedures
When cannabis is being used for medical purposes, it is critical to have continuous monitoring and testing of products. Tests that can help to reduce the risk of contamination as well as improve product quality if dispensaries and growers pay attention to the test results.
Some of the most valuable testing procedures include aflatoxins, mycotoxins, molds, heavy metals testing, residual solvents, pesticide screening, terpenes profiling, and cannabinoid potency. Specific methodologies and instruments underlie every procedure.
When it comes to cannabis testing the most important component is an accurate cannabinoid potency analysis. Depending on how cannabis is grown, the quantity of cannabinoids that is produced will vary. Data is gathered for three main cannabinoids by most testing labs: cannabinol (CBN), cannabidiol (CBD), and tetrahydrocannabinol (THC) and whether they are decarboxylated or carboxylated.
The potency of THC ranges from 5 percent up to 25 percent in edibles and plant material, but in concentrated oils can run a lot higher. To date, there are no standards established for performing extractions, homogenizing samples, and chopping samples. Therefore, potency level variations may exceed 20 percent easily. The two testing methods that are most commonly used for potency testing use high-performance liquid chromatography (HPLC) and gas chromatography (GC) machines.
During the GC flame ionization detector (GC-FID) and GC mass spectrometry (GC-MS) processes, intense heat is used to vaporize samples. That converts any THCA into THC, that is reported as “THC Total” by the lab. Also, HPLC is commonly used for determining how much cannabinoids is contained in the final product. Heating is not required by HPLC machines and generates a more accurate determination of the quantities of decarboxylated or carboxylated forms that a sample contains.
Profiling of Terpenes
Terpenes are produced in a plant’s flowers trichomes and are common components in the distinctive aroma and flavor of cannabis. Also, terpenes act as basic hydrocarbon building blocks, which influences the product’s overall therapeutic and homeopathic effects.
Depending on the weather, climate, the plant’s age, and even the time of the day when it is harvested, cannabis might contain over 120 different terpenes. Terpene characterization, as well as their synergistic effects with cannabinoids, is essential for identifying the best cannabis treatment plan for a patient.
The best way to do this profiling is to use gas chromatography. The only accurate way to quantify and identify terpenes is GC-MS to ensure that they are separated chromatographically from all of the interfering compounds. Cannabis is vaporized by a GC-MS instrument and a natural gas is released that gets carried via a carrier gas through the machine. Terpenes are separated by their affinity for the chemically coated column. The terpenes, after separation, are detected and a computer then quantifies them. High-sensitivity GC-MS systems are able to quantify and qualify components that were previously undetectable and identify over 3,000 fragrance and flavor compounds.
It can be challenging to analytically detect pesticides. Commercial grow operations use pesticides to kill brown marmorated stinkbugs, grasshoppers, caterpillars, spider mites, and mites.
With cannabis plants being threatened by so many insects, it isn’t surprising that there are so many pesticides that are available for getting rid of them. This causes problems since pesticides are mutagenic and carcinogenic and may cause consumers serious harm, especially those that are immunocompromised. There is no lab that is able to screen for every single pesticide, but most of them do test for the most common products: avermectins, pyrethroids, carbamates, and organophosphates.
The combination of liquid chromatography and mass spectrometry (LC-MS/MS) is the instrumentation platform that is preferred for this type of testing. LC-MS/MS enables labs to identify different pesticides in a single cycle, which ultimately reduces costs and run times. However, for analyzing some pesticides, the preferred solution is the complementary GC-MS/MS technique. There are some factors that affect GC-MS/MS or LC-MS/MS use are ionization efficiency, thermal stability, volatility, and polarity of these compounds.
These are the chemicals that are left over from the terpenes and cannabinoids extraction processes. Common solvents include hexane, propane, water, butane, and ethanol, which are evaporated in order to prepare high-concentration waxes and oils. At times it is necessary for large amounts of solvents to be used in order to achieve higher purity levels and increase extraction efficiency.
Realistically, it is nearly impossible for all solvents to be removed following the extraction process. Since residual solvents are not safe for humans to consume, it is critical to verify that all traces of these substances have been eliminated.
GC-MS is the preferred screening technology due to the machine’s ability to individually quantify the solvents. GC-MS also enables users to use an alternative sampling technique, like a headspace unit, in order to improve quality control and assurance.
Heavy metals testing
There are metals contained in fertilizers and soils. As cannabis plants are growing, those metals are drawn in. Heavy metals are toxic, such as mercury, arsenic, cadmium, and lead. Lab testing helps to ensure that products do not contain toxic concentrations.
Several methods can be used for determining trace metals contained in plant materials. Preliminary acid digestion is required by all of them. The most sensitive method is ICP-MS (Inductively coupled plasma mass spectrometry) and quality control labs prefer it for rapidly screening heavy metals.
Precision weighing and moisture content
Typically dried cannabis has a 10 to 12 percent moisture content. A moisture content over 12 percent causes stored cannabis be prone to mold. Since medical users might be very vulnerable to mold effects and be immune-deficient, constant moisture monitoring is necessary. Various precision measuring balances can be used to measure the moisture content of various cannabis samples.
Mycotoxins are a secondary metabolite of mold and toxic. Being exposed to mycotoxins continuously can lead to worse allergic reactions progressively building up, and they can potentially become lethal. Aflatoxins are a mycotoxins subset that is found in decaying vegetation and soil.
Restrictions have been placed by regulatory bodies when it comes to the allowable amounts of mycotoxins contained in food. However, since cannabis is listed as being a Schedule I substance, testing for protecting users is not mandated by the U.S. government. However, many states do test for mycotoxin ochratoxin and aflatoxins A, G2, G1, B2, B1. Removing and testing for mycotoxins rely on scientists working in independent labs and is a critical step in the process of providing effective and safe medical products.
The high sensitivity of liquid chromatography (LC) equipment makes it the perfect platform to screen for mycotoxins. Along with the standard LC, when an MS selective detector is used it allows labs to obtain detection limits up to 1,000 higher compared to when conventional LU-UV instruments are used.
Cannabis testing’s future
As an increasing number of state legalize recreational and/or medical marijuana and even more cannabis-based products are entering into the marketplace, the demand for cannabinoid testing continues to increase. A stronger integration between testing labs with physicians, consumers, dispensaries, extractions, and grow operations is needed in order to ensure quality control and offer essential information on cannabis products.