What Is Tested in a Cannabis Lab

Cannabis labs run a set of tests on flower, concentrates, edibles, and topicals. The core panel covers cannabinoid potency, terpenes, pesticides, heavy metals, microbials, mycotoxins, residual solvents, moisture, water activity, and foreign matter. Some states require all of these. Others require a subset. A few add tests for vitamin E acetate or residual butane in vape cartridges.

Comparison Review: Cannabis Lab Testing Standards

A lab reports results on a certificate of analysis (COA). A batch passes or fails against limits set by the state. Failed batches get destroyed or re-mediated.

what is tested in a cannabis lab

Cannabinoid Potency

Labs measure THC, THCA, CBD, CBDA, CBG, CBN, CBC, and THCVA. Instruments are HPLC with UV or diode array detection, and in some cases GC-MS. Heat in a GC inlet converts THCA to THC, so HPLC is the standard method for acid and neutral forms.

related article

Total THC equals THC plus 0.877 times THCA. The 0.877 factor accounts for the mass lost when the acid group leaves. Labels show total THC and total CBD.

cannabis potency testing explained

Terpenes

Terpene testing uses GC-FID or GC-MS. Labs report myrcene, limonene, linalool, pinene, caryophyllene, humulene, terpinolene, and others. Results come in milligrams per gram or percent by weight. Total terpenes in dried flower land between 0.5% and 4% in most samples.

Pesticides

Pesticide screens use LC-MS/MS and GC-MS/MS. One run can cover 100 or more compounds. State lists differ. Some run past 60 analytes. Common targets include myclobutanil, imidacloprid, abamectin, bifenazate, and paclobutrazol. Limits sit in the parts-per-billion range, often 10 ppb to 500 ppb per compound.

Heavy Metals

Labs test for lead, cadmium, arsenic, and mercury. ICP-MS is the standard method. Limits range from 0.1 ppm to 0.5 ppm depending on the metal and the state. Plants take up metals from soil, water, and nutrient salts.

Microbials

Microbial tests count total aerobic bacteria, yeast, and mold. Plating and qPCR are both used. Limits run from 10^3 to 10^5 CFU per gram. Labs also test for absence of Aspergillus (four species), Salmonella, and E. coli. Aspergillus is a risk in inhaled products.

Mycotoxins

Mycotoxin tests target aflatoxin B1, B2, G1, G2, and ochratoxin A. LC-MS/MS detects them at parts-per-billion levels. These toxins come from mold growth during drying or storage.

Residual Solvents

Solvent tests apply to concentrates, extracts, and vape cartridges. Headspace GC-MS measures butane, propane, pentane, hexane, ethanol, isopropanol, acetone, benzene, and toluene. Limits follow ICH Q3C classes. Benzene is capped near 2 ppm. Class 3 solvents can run to 5,000 ppm.

Moisture, Water Activity, and Foreign Matter

Moisture meters and water activity meters check flower. Moisture targets sit near 8% to 12%. Water activity limits sit at or below 0.65 aw. High water activity supports mold. Foreign matter checks look for stems, seeds, soil, insects, hair, and visible mold.

Sampling and Batch Rules

Results depend on the sample. Labs pull increments from a batch, then homogenize. Flower batches are often 10 pounds or 15 pounds. A bad sample can fail a good batch or pass a bad one. States set batch sizes, sample weights, and retest rules.

What Labs Do Not Test

Most panels do not measure flavonoids, amino acids, or full volatile profiles. They do not test for every possible contaminant. Vitamin E acetate is a required test in some states for vape products. Ask the seller for a COA that matches the batch number on the package.