Cannabis Potency: How Does Lab Testing for THC and CBD Work?

Cannabis testing is essential for anyone looking to purchase cannabis products. By accurately identifying the strength and composition of these products, consumers can make informed decisions on what they buy. This is especially important for medical cannabis patients who need specific therapeutic effects, but it’s also crucial for adult-use consumers because the potency of products can vary widely – resulting in different experiences.

There are a variety of methods for testing cannabis to ensure safety, quality, and potency information to consumers. While the specific testing criteria differ by state, several major testing processes are found across the industry. THC and CBD levels in cannabis products are particularly important when it comes to potency data; as a result, they motivate cannabis analysis firms to provide information on these components.

Testing Cannabis Products for THC and CBD Levels

Cannabinoid potency data refers to the levels of plant cannabinoids present in cannabis products. Producers are required to test for THC and CBD levels, which will largely dictate the effects of the product. For example, some medical patients may want a strains with little-to-no THC, while adult consumers may request a higher ratio.

Although not always necessary, THC and CBD Potency tests can be done for other compounds as well, such as minor cannabinoids and terpenes.

How Do Labs Measure THC and CBD Levels?

There are a variety of ways to measure THC and CBD concentrations. The most widely used method is High Performance Liquid Chromatography (HPLC). HPLC may separate and quantify a mix of chemicals in liquid solution.

In high-pressure liquid chromatography (HPLC), a sample is first collected from cannabis flower mixed with a solvent, such as ethanol. Next, the solution is pumped through a tube under high pressure. This tube contains materials that attract certain molecules in the sample based on their chemical properties. Finally, at the end of column there is a detector; compounds which are attracted to the material inside will travel more slowly and reach it later than others.

UV light absorbance is measured by optical density (OD) HPLC detectors, which may be linked to specific compounds. When the chemicals reach the detector, their relative abundance is determined. Because different cannabinoids, such as THC and CBD, move at various speeds through the column, they will be discovered at varying intervals, allowing for sample characterization.

The cannabis sample is injected into the system and the cannabinoids move through the column. Different rates of travel are based on interactions between the cannabinoids and the column material. The detector quantifies how much of each type of cannabinoid is present, which is indicated by how long it takes to be detected.

The THC and CBD values listed on the back of cannabis packaging come from laboratory measurements. Because these values are referred to directly by consumers for product information, accurate potency testing is crucial.

A strip of white construction paper, a black marker (you may need to get a specific type that will work with this experiment), and a glass of water can be used to conduct your own DIY chromatography experiment at home.

Use a black marker to draw a line parallel to the paper’s edge across the strip. Place the paper strip upright in a glass of water, with the marker line just above the surface.

After you wait a few minutes, the water will travel up the paper and separate out the colors in the marker.

Terpenes are more volatile than cannabinoids and require chromatography for detection. Volatility means that terpenes evaporate easily and exist usually in a gaseous state, whereas cannabinoids are stable in liquid solution. The volatility of terpenes necessitates a different lab technique.

Cannabis Testing Standardization

“Washington state-certified laboratory Confidence Analytics reports that ‘there are no strong regulations in place about how cannabis chemicals are measured.’ However, they do mention that HPLC has become the most popular method for measuring cannabinoids.” It’s important to note that in other industries, specific guidelines exist on testing methods and settings for laboratory equipment. This begs the question: why not set similar standards for assessing cannabis efficacy?

Because the industry lacks regulation, potency data can vary and cannabinoid data may be wrong. States are working to standardize cannabis testing to guarantee that potency values are comparable across laboratories. In Washington state, a group of I-502 licensed labs is conducting a “round robin,” in which they measure the strength of an unknown marijuana sample and compare their findings with those from other laboratories. If each laboratory adheres to proper testing methods, reported potency statistics should be consistent throughout the board.

To maintain both industry transparency and consumer safety, a variety of cannabis product tests should be completed for quality assurance. These include testing for terpenes, contamination, and residual solvent levels using distinct methods in order to collect data.

Unfortunately, potency testing methods have come under fire in recent years, with concerns about possible over-inflating of THC concentration. The requirements for cannabis testing procedures differ significantly from one state to the next, making standardization difficult. As a result, in order to ensure accurate potency reporting, the sector needs to advocate for a general, national quality assurance standard for cannabis testing.