How to Read a Certificate of Analysis
A Certificate of Analysis is the single document that tells you what a research compound actually is. Here's how to read every field on a LOCKED COA — and what each one proves.
By LOCKED Research Team · Analytical Standards
Research Use Only. This article is educational and does not constitute medical advice or a claim of safety or efficacy. LOCKED products are supplied for laboratory research use only (RUO). They are not drugs, foods, dietary supplements, cosmetics, or medical devices, are not for human or animal consumption, and are not intended to diagnose, treat, cure, or prevent any disease. LOCKED makes no medical, therapeutic, or performance claims. The purchaser is solely responsible for compliance with all applicable laws and for lawful use.
A batch number is only meaningful if it resolves to evidence. That evidence is the Certificate of Analysis (COA) — the analytical record generated for a specific batch and tied to a specific lot. Learning to read one is the difference between trusting a label and verifying it.
The header: what and which
Every COA identifies the compound and, where applicable, its sequence and molecular weight. These answer the first question: is this the right material at all? The molecular weight on the certificate should match the known value for the stated compound. A mismatch is a red flag before you read another line.
The header also carries the batch and lot numbers. The batch identifies the production run; the lot identifies the specific fill. Both should match what is printed on your vial.
Identity: is it what it claims to be?
Identity is typically confirmed by mass spectrometry (MS). MS measures the mass of the molecule directly, confirming that the material matches the expected structure — no substitution, no mislabeling. A COA should state that identity was confirmed, not merely assumed.
Purity: how much of it is the compound?
Purity is quantified by reversed-phase high-performance liquid chromatography (RP-HPLC), reported as an exact percentage — never a range. A result of "≥98%" means the analysis resolved the main peak and any impurities and found the target compound at or above that threshold. The number on the certificate is the number in the vial.
Be wary of any document that reports purity as "high" or "lab tested" without a figure and a method. Purity without a number is not a measurement.
Provenance: who tested it, and when?
A complete COA names the testing laboratory and the test date, and states storage conditions. Accredited third-party testing matters: it means the purity figure was produced by a party with no stake in the result. The test date tells you the analysis reflects the material as produced, not an old reference.
Putting it together
Read a COA in this order: confirm the compound and molecular weight, confirm identity by MS, read the purity figure and its method, then check who tested it and when. If every field resolves and the batch and lot match your vial, you are holding documented material.
Every LOCKED order includes the COA, HPLC chromatogram, and mass spectrometry report for its batch — and any lot number can be checked directly through our verification tool.