What Lab Testing Means: Reading a Cannabis Certificate of Analysis

Lab testing is what separates licensed cannabis from everything else. Every product on the shelves at QCD Brooklyn and QCD Staten Island has been tested by an independent, state-licensed laboratory before it reaches you. This guide explains what gets tested, how to read a Certificate of Analysis (COA), and why it should matter to every cannabis consumer.

Why Lab Testing Exists

Cannabis lab testing exists for one reason: consumer safety. During prohibition, there was no way to know what was in the cannabis you purchased. It could contain pesticides, mold, heavy metals, or residual solvents from the extraction process. It could be far more potent — or far less potent — than the seller claimed.

New York State requires all cannabis products sold through licensed dispensaries to pass comprehensive lab testing before reaching the consumer. This is one of the most significant advantages of buying from a licensed dispensary versus an unlicensed source. Read our licensed vs illegal dispensary comparison for the full picture.

What Gets Tested

A comprehensive cannabis lab test covers seven key areas. Here is what each one means:

1. Cannabinoid Potency

This is the most commonly referenced test result. It measures the concentration of cannabinoids in the product, primarily THC and CBD, but also minor cannabinoids like CBG, CBN, CBC, and THCA. Potency is expressed as a percentage (for flower) or milligrams per serving/package (for edibles and tinctures). This is what helps you dose correctly.

2. Terpene Profile

Terpene testing identifies which aromatic compounds are present and in what concentrations. This information helps predict the flavor, aroma, and effects of the product. Common terpenes include myrcene, limonene, pinene, linalool, and caryophyllene. Learn more about terpenes in our Cannabis 101 guide.

3. Pesticide Screening

Cannabis can accumulate pesticides during cultivation. New York tests for dozens of specific pesticides, herbicides, and fungicides. Products must test below established safety thresholds or show no detectable levels to pass.

4. Heavy Metals Testing

Cannabis plants can absorb heavy metals from soil and water. Labs test for lead, arsenic, cadmium, and mercury. Even trace amounts of these metals can pose health risks with repeated exposure, making this screening essential.

5. Microbial Testing

This screens for harmful microorganisms including E. coli, Salmonella, Aspergillus (a common mold), and total yeast and mold counts. Microbial contamination is particularly dangerous for immunocompromised consumers.

6. Residual Solvents

This applies primarily to concentrates and vape cartridges. The extraction process often uses solvents like butane, propane, ethanol, or CO2. Residual solvent testing ensures that no harmful amounts of these chemicals remain in the final product.

7. Moisture and Water Activity

Excessive moisture in weed flower promotes mold and bacterial growth. Labs measure moisture content and water activity to ensure the product is properly cured and safe for storage and consumption.

How to Read a COA

A Certificate of Analysis (COA) is the official document produced by the testing lab. It can look intimidating at first glance, but here are the key sections to focus on:

COA Section	What to Look For
Sample Information	Product name, batch number, date tested, and the name of the testing lab. Verify these match the product you are buying.
Cannabinoid Results	THC and CBD percentages or milligrams. Compare to what is printed on the product label — they should match.
Terpene Results	List of terpenes detected and their percentages. Useful for predicting flavor and effects.
Contaminant Results	Pesticides, heavy metals, microbials, and residual solvents. Each should show “Pass” or “ND” (not detected) or results below the action limit.
QR Code / Lab Website	Many COAs include a QR code or URL linking to the full results on the lab’s website. This lets you verify the document is authentic.

What the Numbers Mean

When reading a COA, you will see results expressed in different units:

• Percentage (%): Used for flower potency. A flower with 25% THC contains 250mg of THC per gram.
• mg/g (milligrams per gram): Common for concentrates. A concentrate at 800mg/g is 80% THC.
• mg/serving or mg/package: Used for edibles and tinctures. A package of gummies might contain 100mg total THC with 10 pieces at 10mg each.
• ND (Not Detected): The substance was not found at detectable levels. This is what you want to see for contaminants.
• Pass/Fail: Some results are binary. A “Pass” means the product met the regulatory threshold for that test.

QCD’s Commitment to Lab-Tested Products

At Quality Control Dispensary, the name is the mission. We only carry products from licensed brands that have passed all required New York State lab testing. We do not cut corners, and we do not sell products that have not been verified by independent laboratories.

Our budtenders can pull up COAs for any product on our shelves. If you want to see the lab results before you buy, just ask. We believe transparency builds trust, and trust is what keeps our customers coming back to our Brooklyn and Staten Island locations.

How to Ask for a COA at QCD

It is simple: just ask your budtender. You can say something like, “Can I see the lab results for this product?” or “Do you have the COA for this batch?” Our team is trained to answer these questions and will happily walk you through the results.

You can also look for COA information on product packaging. Many brands we carry include QR codes on their labels that link directly to lab results online.

If a dispensary cannot or will not provide lab results, that is a significant red flag. It could mean the products have not been tested — which means they could contain contaminants that pose real health risks. This is one of the key differences between licensed and unlicensed dispensaries.

Frequently Asked Questions

What is a Certificate of Analysis (COA)?

A Certificate of Analysis is an official document from an independent, state-licensed testing laboratory that details the results of tests performed on a specific batch of cannabis. It includes cannabinoid potency, terpene profiles, and screening results for contaminants like pesticides, heavy metals, microbials, and residual solvents.

Can I ask to see a COA at a dispensary?

Yes. You have every right to ask for a COA at any licensed dispensary. At Quality Control Dispensary, our budtenders can pull up lab results for any product on our shelves. If a dispensary cannot or will not provide a COA, that is a red flag.

What does THC percentage mean on a label?

The THC percentage on a label represents the total THC content as a percentage of the product’s weight. For flower, typical THC percentages range from 12% to 35%. A higher percentage means more THC per gram, but it does not necessarily mean a better experience — terpene profiles, consumption method, and individual tolerance all play significant roles.

Are all marijuana products in New York lab tested?

All cannabis products sold through licensed New York dispensaries must pass mandatory lab testing before reaching the shelf. However, products from unlicensed sources — illegal smoke shops, street vendors, or unlicensed delivery services — have not been tested and may contain harmful contaminants. This is one of the most important reasons to buy from a licensed retailer.

Last updated: April 29, 2026