Why you want cannabis lab testing

Just like with all medical products available today, lab testing is important to make sure you get a standardized dose and strength. You want to make sure your medical marijuana doesn’t contain harmful pesticides, compounds, or microbial organisms that can compromise your health. Another safeguard you should know is the potency of your medical marijuana. If your doctor recommends you start with a low dosage, you need to know the product you’re using meets that requirement.

Another reason you should look for lab-tested medical and recreational marijuana is the cannabis plant is a veritable sponge. It soaks up everything in its environment; if your marijuana comes from a grow situated by a farm that uses pesticides, it might retain those pesticides in its final product. Specifically, you want your cannabis tested for solvents, pesticides, mycotoxins, heavy metals, and a microbial like mold and fungus.

Ask your marijuana dispensary to see a “Certificate of Analysis” for the strain you’re considering purchasing. This certificate should show you the acceptable levels and what your strain tested at for each element. It’s your responsibility to make sure your products are free of unnecessary chemicals, organisms, pests, etc., that can compromise your health. Also, a lab should test for potency, showing you how much THC ad CBD your product contains.

As cannabis becomes legal around the United States, expect standards and regulations for testing facilities to evolve in the years to come. In the meantime, educate yourself so you know what to look for on a “Certificate of Analysis.”

A note of caution

First and foremost, be wary of dispensaries that don’t test their products. Some states in the US don’t require lab testing yet because the marijuana industry is still in its infancy. Expect states with a more experienced industry to have testing regulations and standards, like California, Oregon, and Washington. Other states are working hard to figure what to test for and what are acceptable levels. Some are taking a “wait and see” attitude before they legislate testing measures.

If you’d like to know your particular state’s stance on cannabis testing, Leafly has a wonderful guide that details regulations by state as of August 2017. Note, however, this listing was last updated in 2017. To make sure you’re using current information, research marijuana regulations in your particular state.

What to look for in test results

Tests can vary wildly from state to state. Most cannabis labs today test for physical contaminants, any residual solvents, a microbial like E.coli, terpenes, potency such as the THC and CBD levels, chemical contamination, and heavy metals. Let’s look at each in more detail.

Physical contaminants

Production facilities should be neat and clean. Raw materials should never be handled without gloves or contact the floor in any way. If your cannabis product was handled on clean surfaces, it should test negative for physical contaminants like dust, hair, fecal matter, and more.

Residual solvents

Solvents such as carbon dioxide, water, butane, ethanol, and other materials can become toxic in quantities. Testing for these solvents shows you if there were large volumes of each used in growth and production. Sometimes these elements are used to achieve higher purity amounts and to make extraction easier. You’re looking for a residual solvent that’s left after the manufacturer processed the marijuana. Residual solvents are usually measured in a parts per million (ppm) amount.


Microbials pose a safety hazard. While testing is a bit laborious, a serious lab will test for relevant microorganisms. They will use a variety of procedures including sound assay design and validation and statistical sampling. The water level in cannabis is where you’ll find microbial content. If the curing process wasn’t complete and thorough, you might find E.coli, Pseudomonas aeruginosa, or Clostridium botulinum.


A terpene analysis measures the amount of fragrance and flavor your medical cannabis contains. This analysis measures gas and liquid chromatography to determine the sample’s terpene content. A terpene analysis is how you can determine a strain’s flavor profile to help you choose the right one for your needs and tastes.


Cannabinoids are the active ingredients in cannabis. The two most common—and sought after—cannabinoids are THC (the psychoactive ingredient) and CBD (non-psychoactive medicinal element). Other cannabinoids labs might test for include tetrahydrocannabinolic and cannabidoic acids, CBC, CBG, THCV, THCA, CBDA, etc. To test for potency, the lab uses gas or liquid chromatography.

Chemical contamination

Growers might use pesticides and other chemicals in the production of both medical and recreational cannabis. To make sure you’re not ingesting unhealthy levels of chemicals, expect a chemical contamination lab test. Similar to the food you buy at the grocery store, you expect the level of chemical contamination to be within the standard for your product.

Heavy metals

Like anything else you ingest, inhale, or introduce into your body, cannabis can contain heavy metals it receives from the soil or other growth medium. Certain heavy metals like lead, mercury, or cadmium can have adverse health effects if taken in quantities. Look for a heavy metals test to find out what and how much is in your medical/recreational marijuana.

What a reputable lab must have to run these tests

Testing labs are not mere fly-by-night operations. They require expensive equipment and extensively trained personnel to run the necessary tests. Much like pharmaceutical testing, stringent adherence to procedures and the use of specific tools guides testing of each sample submitted. Before the cannabis sample hits the lab equipment, however, it goes through a vigorous visual inspection for signs of mold or other contamination. Once cleared visually, it moves on to more stringent tests.

Here are a few of the elements you can expect in a legal marijuana testing lab.

  • Mass spectrometers. This equipment identifies particles in a cannabis sample. It uses a heating process to detect the number of particles. In fact, since the process is similar, a lab can use a gas chromatograph equipped with a mass spectrometer and a thermal conductivity detector to generate the same results.
  • Analytical chromatography. Another procedure a lab could use to determine the presence and concentration of particles in the marijuana is the gas chromatography and liquid chromatography. Labs widely use these two methods in the cannabis industry. They might also use a high performance liquid chromatography because the gas one uses high heat which increases the weed’s psychoactive effects.
  • NMR (nuclear magnetic resonance spectroscopy). Using the gas and liquid testing procedures discussed above requires a lot of solve and are time-consuming. Expertly equipped labs use an NMR that doesn’t destroy the samples or use solvents and has a much shorter time to results. Without getting too technical, the NMR uses magnetic fields to determine the structure of the cannabis’s molecules and its chemical compounds.
  • PCR (polymerase chain reaction) machines. These machines can test for bacteria, mold, tester, or fungus, but it can also test down to the DNA molecule level. In addition, the PCR is fast; you can usually get results within an hour, far faster than any of the previously mentioned tests.

Who works in cannabis testing labs

From degreed chemists to experienced bud tenders, understanding who works in a licensed cannabis testing lab underscores the immensity of the certification process.

  • Analytical chemist. These chemists understand labs and tests intimately. They have extensive experience and training on the lab equipment used like gas chromatographs and mass spectrometers. They’re in charge of lab technicians to make sure they’re using the equipment properly. An analytical chemist is an expert in understanding and reviewing raw analytical data as well as the proper handling and preparation of samples. These chemists take a lead role in developing new testing methods and they have an in-depth understanding of pesticides, solvents, and other testing elements. A reputable lab requires their analytical chemists to have a Ph.D., Master’s, or Bachelor’s in chemistry or a similar field, with valid experience with the testing equipment.
  • Extraction technician. The extraction technical prepares the samples and equipment for testing. They’re the ones who extract the cannabinoids for testing. When hiring extraction technicians, a licensed cannabis testing lab looks for someone with extensive experience as an extraction technical and a background in inorganic and organic chemistry. For example, a technician with oil extraction experience would be eligible as well as a technician experienced with flammable storage cabinets and CO2 extraction processes. Like the chemist, the extraction technician must know how to prepare and maintain the equipment. For example, they should be able to adjust the centrifuges, microscopes, and more. An Associate’s or Bachelor’s in chemistry is a must.
  • Other positions. Labs also need managers who can coordinate all the samples and their testing. For example, a lab might need a manufacturing manager, a testing manager, and an account manager to coordinate its flow of samples to test.

Most colleges and universities offer degrees in chemistry and the necessary experience with equipment for those interested in a cannabis lab career. For example, technical institutes offer hands-on experience and training with equipment, testing methods, and troubleshooting techniques.

Final thoughts

It’s better to fall on the safe, tested side of the equation. Look for dispensaries that carry marijuana strains tested by licensed labs. You only want weed free of residual pesticides, unwanted contaminants, and a microbial like mold and mildew. And make sure you know the level of THC and CBD in your strain to make sure you’re taking the right strength and dosage. Finally, look for A2LA Cannabis Testing Laboratory Accreditation. This organization accredits testing labs for legalized cannabis testing procedures and standards. Their goal is to promote confidence in the cannabis you buy as to its safety for both medical and recreational use.

Christopher Wright

Meet Christopher Wright, aka Blue, successful radio host and creator of Cannabis Talk 101. As well as CEO of Cannabis Talk Network. For over a decade now, Chris has had his hands in all faucets of the Cannabis Industry. From medicinal marijuana dispensaries and cultivations to controversial cannabis activism, Chris is a pioneer for the cannabis movement.