What is a Certificate of Analysis?
A Certificate of Analysis is a document issued by an analytical laboratory that reports the test results for a single, identified batch of material. For a research compound it records the methods used, the measured purity, the identity confirmation, and a batch or lot reference that ties the paperwork to the physical vial.
Because each COA is tied to one batch, it is evidence about that batch specifically — not a general statement about the compound. The lot number is what connects the certificate to the material in front of you.
What does each section of a COA show?
Most certificates follow the same structure. The fields below appear on a typical research-compound COA, with what each one reports and how to read it.
| Section | What it reports | How to read it |
|---|---|---|
| Compound & batch/lot | The compound tested and a unique batch or lot reference | Confirm the name matches and the lot matches the number printed on your vial |
| Test method | The analytical techniques applied (e.g. HPLC, MS) | Identifies how purity and identity were established |
| Purity result | The measured purity, usually as a percentage by HPLC | Compare against the stated purity standard (e.g. 99%+) |
| Identity result | Molecular weight / identity confirmation by mass spectrometry | Verifies the material matches the labeled compound |
| Laboratory | The lab that performed the analysis | An independent, named lab indicates third-party testing |
| Date of analysis | When the batch was tested | Establishes when the reported results were generated |
How do you interpret the purity result?
Purity on a COA is most often reported as a percentage derived from an HPLC chromatogram — the proportion of the total signal attributable to the target compound. A result of 99% means the target accounts for 99% of the measured material, with the remainder being related impurities.
Read the purity figure against the stated standard rather than in isolation. A certificate that reports the method (HPLC), the percentage, and the standard it is measured against is more informative than a bare number with no method attached.
How is identity confirmed on a COA?
Purity tells you how much of the sample is the target; identity tells you the target is actually the labeled compound. Identity is established by mass spectrometry, which measures the molecular weight of the material and checks it against the expected value for that compound.
A complete certificate pairs a purity method (HPLC) with an identity method (MS). Together they answer two separate questions: how pure, and pure of what.
How do you match a COA to your batch?
Every vial carries a lot number. That number is the link between the physical batch and its certificate: matching the lot on the vial to the lot on the COA confirms the document describes the material you actually hold.
If the lot numbers do not match, the certificate is for a different batch. Requesting the COA that corresponds to your specific lot is the way to confirm the results apply to your material.