A Certificate of Analysis, often called a COA, records laboratory test results for an identified sample. A page of numbers can look complicated at first. Reading it in a set order makes it easier to understand what was measured and what the report actually says.
Begin with the details that connect the document to the sample. Then move to the test tables, their units and the laboratory’s notes.
Start with the sample details
Look for the sample name, sample type, batch or lot identifier, and laboratory name. A sample ID may be the laboratory’s own reference number. Do not assume that it is the same as the batch number printed elsewhere.
Compare the available identifiers before reading the results. If the names or numbers differ, ask the issuer to explain the connection. A similar name alone does not establish that two records refer to the same material.
Give each date its own meaning
A report may show several dates. The collection date records when the sample was taken. The received date records when the laboratory received it. The reported date identifies when the report was issued. Check the report status as well: a document marked as preliminary should not be read as a final report.
Keep these dates separate in your notes. A report date is not automatically a manufacture date or an expiration date.
Read the column headings before the numbers
A test table lists the substances or properties examined, often called analytes, alongside results and other details. Read the full row, including the unit and any footnote marker.
Milligrams per gram, milligrams per milliliter and percentages express quantities in different ways. A number without its unit is incomplete. Before comparing two results, confirm that they describe the same substance, use compatible units and refer to the same reporting basis.
Understand the small abbreviations
- LOD: the limit of detection, which concerns the smallest amount a method can distinguish from background.
- LOQ: the limit of quantification, which concerns the smallest amount the method can measure reliably.
- ND: commonly used for “not detected.” Read the report’s legend to confirm how that laboratory uses it.
“Not detected” is not the same as a proven quantity of zero. A result below a stated limit also should not be treated as an exact measurement. The method and reporting limits give those entries their meaning.
Keep the conclusions within the report
Check which tests appear and whether the document includes additional pages. A pass or fail entry relates to the test and criteria identified in that report. Do not extend it to properties that were not examined.
Save the complete document when you need a record. A cropped screenshot can remove the sample details, units or notes needed to interpret a result. If a field remains unclear, ask the issuing laboratory about that specific field and include the report number.
Sources: The New York Office of Cannabis Management explains common COA fields; Health Canada explains detection limits, units and reporting; and California’s Department of Cannabis Control describes test categories and COA results. These references explain document terminology; requirements vary by context.