How does cannabis testing work?

a year ago   •   2 min read

By Juana Know Staff

The process of cannabis testing has yet to be standardized in the United States. A group  known as The Cannabis Alliance is working to promote standardized testing. At the moment there's a lack of clarity in the law on how chemicals in cannabis products are measured in the industry. Here's a look at current marijuana testing and how it works.

Testing for Cannabis Potency

The lack of regulations for standardizing equipment that measures cannabinoids has sometimes led to flawed or misleading test results. One of the main reasons for cannabis testing is to measure its Tetra-Hydro-Cannabinol level, which defines potency in terms of euphoric effects. T-H-C and C-B-D are both molecules classified as cannabinoids that "turn on" receptors in the brain. Cannabis testing includes measuring CBD levels, which are responsible for the plant's medicinal qualities. CBD, as many marijuana patients have learned, doesn't produce an intoxicating effect.

One of the emerging controversies of the medical marijuana industry is that some companies have inflated chemical concentration levels in their labels based on their own testing methods. Since regulations on cannabis vary from state to state, it's difficult to compare testing methods and results across the nation. Identifying which states deliver the most accurate testing would be very challenging at this stage. Adopting national standards would help bring about a more clear consensus on cannabis content and dosage.

Measuring Concentration Levels of Cannabis Components

The purpose of THC testing is to determine its concentration in cannabis. Since it's the psychoactive ingredient that enables the "head in the clouds" feeling when one consumes highly potent cannabis, many patients are interested in the tetrahydrocannabinol level. For recreational marijuana connoisseurs, a higher concentration of this cannabinoid is desired. But some medical marijuana patients just want the medicinal effects from the CBD concentration.

How It Works

The most common practice in labs for measuring chemical compound levels in cannabis is called High-Performance Liquid Chromatography (HPLC). This technique involves separating and quantifying chemicals within a liquid mixture. Since different molecules move at different speeds in a liquid solution, they can be identified by their speed with HPLC detectors, which measure UV light absorbance. The reason this data is important is that certain degrees of absorbance are linked to specific molecules.

The HPLC test is usually the source for cannabinoid concentration data on cannabis packaging. It can also be used, however, by employers to determine whether a person has consumed cannabis within a certain time period, not whether they are intoxicated. These tests are conducted with samples of urine, oral fluid, or hair.

Future of Marijuana Testing

The future of more accurate and reliable marijuana testing for determining levels of its components in the plant appears to involve nanotechnology. Sensors 100,000 times smaller than human hair made of carbon nanotubes are now being tested at the University of Pittsburgh. These sensors measure the speed at which molecules leave the chip. Certain molecules like THC travel at a slower speed and stay on the chip longer than more common compounds. Machine learning will also play a prominent role in accurately measuring THC and CBD concentrations.


While there are various forms of cannabis tests in the United States, standardization of testing would help deliver more accurate results, such as with determining component percentages in a cannabis sample. The use of HPLC detectors is paving the way toward better methods of measuring cannabis content, but nanotechnology will likely provide better insights.

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