Everything you need to know
A Certificate of Analysis can look intimidating if you're seeing one for the first time — but once you know what each section means, COAs become a powerful tool for evaluating supplier quality and making compliance decisions. This guide walks you through every section of a typical analytical COA.
What information should appear at the top of a COA?
The header section of a credible COA should include: Laboratory name and contact information — the issuing lab's name, address, phone, and email. Accreditation information — ISO 17025 accreditation number or accreditation pending statement, accreditation body name. Report number — a unique identifier for this specific test report. Date of receipt — when the sample arrived at the lab. Date of analysis — when testing was performed. Date of report — when the COA was issued. Product identification — product name, lot number, and who submitted the sample.
What do the columns in a COA results table mean?
A typical COA results table contains: Analyte — the specific substance being measured (e.g., "Lead (Pb)", "Aflatoxin B1", "Ethanol"). Method — the analytical method used (e.g., "ICP-MS", "LC-MS/MS", "Headspace GC-MS", "USP <467>"). Limit of Quantitation (LOQ) — the lowest concentration the method can reliably measure. Result — the measured value with units (ppm, ppb, µg/g, %). Specification or Action Level — the limit the result is compared against. Pass/Fail — whether the result meets the specification. A result of "<LOQ" or "ND" (not detected) means the analyte was not found above the detection limit — this is a passing result.
What does "ND" or "
"ND" means "Not Detected" — the analyte was not found above the method's limit of detection (LOD). "<LOQ" means the analyte was detected but below the limit of quantitation, meaning the signal is present but too low to reliably assign a precise numerical value. Both ND and <LOQ are effectively "non-detect" results and represent passing results in most regulatory contexts. The key quality check is that the LOQ is low enough to be meaningful — for heavy metals in a supplement tested to Prop 65 limits, an LOQ of 0.01 ppm is appropriate; an LOQ of 5 ppm would be useless because it's higher than the regulatory limit.
How do I know if a COA is credible or potentially fraudulent?
Warning signs of a suspicious or fraudulent COA: (1) No method reference — a credible COA always cites the analytical method. (2) Round numbers only — real lab results are rarely round numbers; "1.000 ppm" for every analyte is suspicious. (3) Unrealistically low LOQs — claims of 0.000001 ppm LOQ without supporting method validation. (4) No laboratory contact info — a credible lab provides contact details and can be independently verified. (5) Generic or stock lab names — verify the lab exists by searching the accreditation body's online directory. (6) COA from the manufacturer itself — a self-issued COA from the product's own manufacturer is not independent.
What should acceptance criteria or specifications on a COA reference?
Acceptance criteria on a COA should reference a recognized standard. Common references include: California Prop 65 — MADLs and NSRLs for heavy metals; widely used as supplement industry benchmarks. FDA action levels — for aflatoxins (20 ppb), fumonisins (4 ppm in human food). USP/BP specifications — for pharmaceutical excipients and actives. EU MRLs — for pesticide residues and mycotoxins in products intended for EU markets. Customer specifications — some COAs note "Per customer specification." If a COA only says "Pass" without referencing what standard defines passing, ask the lab for the underlying specification.
What should I do if a COA result shows a failing value?
A failing COA result does not necessarily mean you discard the lot — it means you need to investigate: (1) Verify the result — request a retest of the retained sample to confirm it's not a lab error or sample prep issue. (2) Trace the source — if heavy metals are elevated, test your raw ingredients separately to identify which ingredient is the source. (3) Consider blending — in some cases, high-contamination lots can be blended with compliant lots to achieve an overall compliant result (check regulatory guidance for your specific situation). (4) Do not ship — do not distribute the failing lot until the investigation is resolved. (5) Notify suppliers — if a supplier's raw material is the source, issue a formal complaint. Need retesting? Request a test here.