How to read a Certificate of Analysis
The five fields to check on any COA — lot number, laboratory and date, identity, purity and appearance — and what each one tells you.
ALORA Research editorial teamPublished Last reviewed 2 min read
The short answer
A Certificate of Analysis (COA) is a laboratory's report on one specific lot of material. To read it, check five fields in order — the lot number, the laboratory and test date, the identity result, the purity result and the appearance check — and confirm the lot number matches the vial in your hands.
A Certificate of Analysis (COA) is a laboratory's report of the tests performed on one specific lot of material and the results it measured. It describes that batch only — not the compound in general, and not any other lot.
1. Lot number
Start here. The lot number on the report must match the one printed on your vial label and packing slip. If it doesn't, the report is not for the material in your hands. ALORA lot numbers start with ALR- and each has its own page in the COA library.
2. Laboratory and test date
A useful report identifies who performed the analysis and when. "Third-party tested" on its own tells you very little; a named laboratory and a test date let you place the result in time and context.
3. Identity
Identity testing confirms that the sample is the stated compound. On ALORA reports this is done by electrospray mass spectrometry (ESI-MS), which compares the measured molecular mass with the expected mass of the molecule.
4. Purity
Purity is the share of the sample that is the target peptide, measured by reversed-phase HPLC. The main peak on the chromatogram is the target; smaller peaks are related substances. A purity figure describes that batch as measured — it is not a standing claim about every lot.
5. Appearance
A documented visual check that the lyophilized material looks as expected for the compound — its colour and form.
Sample records
While a lot is awaiting laboratory results, its page in the library may carry a "Sample record" badge. Sample records show how a report reads; they are replaced with the laboratory's results when that lot is tested, and their values should not be read as measurements.
