How to understand cannabis tests

Lab testing is an essential part of legal cannabis. Any cannabis product you purchase from a licensed facility must undergo tests by a state-accredited lab.

Why are these tests required? 

Gone are the days where you had no idea what you were smoking. These tests help ensure that products are: 

• Safe to consume 

• Easy to dose

• Meeting state compliance

For a cannabis product to be approved for distribution and sale, it must pass testing protocols mandated by the state. Cannabis producers need this compliance data so their products can legally go on the market. 

Labs that conduct these tests must be accredited – the facilities are fully equipped with proper testing equipment, and the technicians have the appropriate education and training. This isn’t some stoner growing weed in his garage; these are highly trained, licensed chemists and microbiologists who understand analytical chromatography. 

What do these tests…test?

Lab tests mainly measure:

• Potency and levels of THC and CBD

• Contamination, such as pesticides, the presence of mycotoxins, or heavy metals

• Comprehensive cannabinoid and terpene profiling

Potency

Potency tests tell you how much THC and CBD are present in a product.

It can be measured in a few different ways:

• Cannabinoid per weight
  Ex. 20% THC

• Total cannabinoids present
  Ex. 150mg THC

• A ratio of THC to CBD
  Ex. 2:1 CBD:THC

Contamination

Between cultivation and processing, cannabis products go through many hands before reaching the dispensary shelf. Throughout its journey, contaminants have the potential to be introduced from various sources.

Lab testing for contamination falls under three major categories:

1. Chemical contaminants

During cultivation, plants can be exposed to pesticides or other chemicals in the soil, like artificial growth hormones. These can be dangerous for consumers, and state regulations have a list of chemicals that must not be present in cannabis products for them to meet compliance. 

With some concentrates and extracts, solvents are required for extraction, so testing for residual solvents like butane, ethanol, and xylene is needed. Small quantities of residual solvents are allowed in products, and that maximum amount varies in each legal state. Clearly California products test non-detect on all solvents.

2. Microbial contaminants

Cannabis risks microbial contamination during cultivation or packaging and handling if staff practices poor hygiene. While mold and fungus are more significant concerns, bacteria like Salmonella and E. Coli are potential contaminants. 

Mycotoxins such as fungi, mold, and mildew in cannabis can be dangerous if ingested. They are  especially dangerous for people who suffer from existing medical conditions or are immunocompromised. 

3. Physical contaminants and heavy metals

If products are poorly cultivated or poorly packaged, physical contaminants like dirt, dust, hair, and (unfortunately) even fecal matter can potentially find their way into cannabis products.

Plant roots can absorb heavy metals present in soils. Heavy metals, including lead, mercury, and cadmium, can also find their way into cannabis products. 

Cannabinoid & Terpene Profiling

As discussed in How to use cannabinoids and terpenes to pick strains, identifying cannabinoid and terpene composition and how they combine to create unique effects can help us understand its effects. These tests are not required for compliance, but they help the consumer better understand the strains on the shelves.

These composition tests will screen for the presence of major terpenes (like myrcene, limonene, linalool, alpha-pinene, beta-pinene, caryophyllene, and terpinolene) and the presence of major cannabinoids (like THC, THCA, THCV, CBD, CBDA, CBG, CBC, CBN, and others).

Major Types of Cannabis Tests

Are you a fan of the science behind all this? Here are some of the main tests used to test the product samples.

Analytical Chromatography

What it does: This test measures the presence and concentration of the various compounds in a cannabis sample.

How it works: First, a sample is dissolved into a fluid poured through an absorbent. Different compounds move through the absorbent at different speeds, leaving colors behind. This colored separation helps testers identify which compounds are present and how much. 

There are multiple methods of chromatography, but the cannabis industry mainly uses high-performance liquid chromatography (HPLC), liquid chromatography (LC), and gas chromatography (GC). GC is the least desirable test because it adds a lot of heat to samples which causes it to decarboxylate cannabinoids (thus affecting the test results). 

Mass Spectrometry (MS)

What it does: MS measures the masses of molecules and chemical compounds within a sample.

How it works: Testers will ionize compounds and subject them to an electric or magnetic field. The deflection rate of the compounds can be displayed in a spectrum to be analyzed. The results are categorized by their mass-to-charge ratio.

Nuclear Magnetic Resonance Spectroscopy (NMR)

What it does: NMR measures the magnetic fields around atomic nuclei. 

How it works: A sample is placed in a magnetic field and bombarded with radio waves, which excites the nuclei and causes it to become detectable by radio receives. Testers measure the change in frequency of the magnetic fields, collecting data on the structure of molecules and chemical compounds. 

NMR is becoming more widely used by labs because it does not destroy samples or use solvents like GC and HPLC. It also has a much shorter turnaround time and is cheaper than tests that use solvents. 

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