How to Read a Certificate of Analysis for Homemade Edibles What Potency Contaminants and Accreditation Actually Mean

A Certificate of Analysis, commonly called a COA, is the primary document that shows what a laboratory measured in a specific sample. For makers of homemade edibles who want more consistent results, learning to read a COA is more useful than relying on strain names or word of mouth descriptions. A COA shows the methods used, the amount of cannabinoids detected, and whether common contaminants were tested and at what limits.

The first section to check on any COA is sample information and chain of custody. This section commonly includes sample name, batch or lot number, product type, date received, date analyzed, date issued, client name, and a QR code or link to verify the digital version. The QR code shown in the photo links to a verification page that allows you to confirm that the paper copy matches the digital record held by the laboratory. Chain of custody is important because results relate only to the submitted sample, not to other batches or future batches. If batch numbers do not match the product you have, the COA does not apply to your material.

The second section to check is laboratory accreditation. Accreditation indicates that a laboratory has been assessed by an independent body for competence and quality management. One commonly reported accreditation in testing laboratories worldwide is ISO IEC 17025, which is an international standard for testing and calibration laboratories. In the United States, many laboratories also list A2LA accreditation, which is an accreditation body that assesses laboratories to ISO IEC 17025, and state programs such as CA ELAP for environmental laboratories. Accreditation does not guarantee that every result is perfect, but it indicates that the laboratory uses validated methods, calibrated equipment, documented procedures, and regular proficiency testing. The photo shows ISO, A2LA, and CA ELAP marks on the same COA, which is an example of how laboratories display multiple accreditations.

The core of a COA is the cannabinoid potency table. This table commonly lists each cannabinoid, result in milligrams per gram or milligrams per milliliter, result as a percentage, LOQ which means limit of quantitation, and method such as HPLC DAD. LOQ is the lowest concentration that the laboratory can reliably measure and report. If a result is listed as less than LOQ, such as less than 0.05 percent, it means the compound was not detected above the laboratorys ability to reliably quantify it, not necessarily that it is absent at any level. HPLC DAD, which stands for high performance liquid chromatography with diode array detection, is a commonly reported method for cannabinoid potency because it can separate cannabinoids without heating that would cause decarboxylation during analysis.

Two calculations in the potency table are especially important for edible makers. Total CBD is commonly calculated as CBD plus CBDA multiplied by 0.877. Total THC is commonly calculated as delta 9 THC plus THCA multiplied by 0.877. The 0.877 factor accounts for the molecular weight lost as carbon dioxide when THCA converts to THC during decarboxylation, and similarly when CBDA converts to CBD. For example, if a sample contains 0.28 milligrams per gram of delta 9 THC and less than 0.05 milligrams per gram of THCA, total THC is calculated as approximately 0.28 milligrams per gram, which is 0.028 percent. If a sample contains 32.45 milligrams per gram of CBD and less than 0.05 milligrams per gram of CBDA, total CBD is approximately 32.45 milligrams per gram, which is 3.245 percent. To convert milligrams per gram to total milligrams in a package, multiply by total weight in grams. For example, 32.45 milligrams per gram multiplied by 100 grams equals 3245 milligrams total CBD in that sample.

The potency summary often translates these laboratory numbers into plain language. In the example shown, total THC of 28 milligrams per 100 gram sample is 0.028 percent, which is below 0.3 percent delta 9 THC, a threshold commonly referenced in hemp regulations in the United States under the 2018 Farm Bill. Compliance statements vary by jurisdiction, and a statement that a product is compliant in one place does not mean it is compliant everywhere. Always check local regulations in your area.

Beyond potency, a full COA includes contaminant testing. Common contaminant sections include heavy metals, microbial contaminants, and pesticides. Heavy metals commonly tested include arsenic, cadmium, lead, and mercury, with limits expressed in parts per million. For example, a result of arsenic less than 0.10 parts per million means arsenic was not detected above 0.10 parts per million. Microbial testing commonly includes total yeast and mold, E coli, and Salmonella. Results are often expressed as colony forming units per gram, abbreviated as CFU per gram, or as absent or present. For example, total yeast and mold less than 100 CFU per gram indicates low counts. Pesticide testing is often performed by LC MS MS, which stands for liquid chromatography tandem mass spectrometry, and can screen for dozens of pesticides at low levels. A result of pass with none detected above LOQ means no pesticides on the tested list were found above the laboratorys quantitation limit.

For homemade edible production, a COA can be used to estimate per serving potency more accurately than using only label claims. If you know total THC or total CBD in milligrams per gram of starting material, you can estimate potential milligrams before infusion loss using grams of material multiplied by percentage as a decimal multiplied by 1000 multiplied by 0.877 for acid forms. You can then account for recovery after straining by measuring starting and recovered oil volume. For example, if you start with 500 milliliters of oil and recover 380 milliliters after straining, recovery is 76 percent. If your pre loss estimate was 350 milligrams, estimated recovered potency is 350 multiplied by 0.76 equals about 266 milligrams in the recovered oil, before accounting for infusion efficiency. This remains an estimate. Only laboratory testing of the finished infused oil can confirm actual milligrams per serving because decarboxylation efficiency, infusion time and temperature, and emulsion uniformity all vary.

Documentation practices improve consistency. For each batch, log batch number, date made, COA reference if available including laboratory name, sample ID, date analyzed, total THC and total CBD percentages, LOQ values, and any contaminant results that are relevant to safety. Also log decarboxylation temperature verified by a calibrated thermometer, time, infusion temperature readings at intervals, carrier type and amount, straining method, starting and recovered volumes, and sensory notes. The photo shows a handwritten review note with batch 1129 marked as pass and compliant, plus initials and date, which is an example of a simple verification log used in many small production environments.

Storage and handling after production affect stability. Cannabinoids can degrade with exposure to light, heat, and oxygen. THC can convert to CBN over time under such conditions, and CBN is commonly described in horticulture literature as being associated with more sedating effects. To slow degradation, store finished products in opaque, airtight, child resistant containers in a cool dark place with minimal headspace, and label with batch number, date made, carrier type, estimated milligrams per serving if calculated, and full ingredient list including common allergens. Keep all products locked and out of reach of children and pets.

A COA is a tool for transparency, not a guarantee of effects. Effects from edibles can vary by individual, dose, tolerance, food intake, and other factors, and may be delayed up to two hours after consumption. Use COAs to compare batches, to verify that testing was performed by an accredited laboratory with documented methods, and to understand what was not detected above LOQ. When a COA does not include accreditation, method, LOQ, or verification information, it is less verifiable than one that does.

This content is educational for adults of legal age where such activity is lawful and does not constitute medical or legal advice. Keep all products in child resistant packaging, locked and out of reach of children and pets. Do not drive or operate machinery after consumption. Effects from edibles may be delayed up to two hours. Start low and go slow. Follow local laws.