What is a Certificate of Analysis (COA)?

A COA is a laboratory report describing the testing performed on a specific batch (lot) of material and its results. A meaningful peptide COA answers three independent questions, each with a different test:

1. Identity — “Is this the peptide on the label?” Confirmed by mass spectrometry (MS): the correct sequence has a specific, predictable mass; a wrong or truncated compound shows a different mass [5][6].
2. Purity — “How much is the target peptide, and what's the rest?” Measured by HPLC, reporting the target as a percentage of the total, with characterized impurities [5][6].
3. Contamination — “Is it free of bacterial endotoxin?” Measured by the LAL endotoxin assay against pharmacopoeial limits (e.g., USP <85> / Ph. Eur. 2.6.14) [7][8].

A point most marketing skips

Purity and endotoxin are not the same thing. HPLC and MS assess identity and chemical purity but cannot detect endotoxin at all — a peptide can be “99% pure,” identity-confirmed, and still carry significant endotoxin contamination. Endotoxin needs its own test [7][8].

How to read a COA

Look for: the compound name and lot/batch number; the named testing lab (ideally accredited, e.g., ISO 17025); the test date and methods; an HPLC chromatogram (usually one dominant peak) and a purity percentage; a mass-spec result (observed vs. theoretical mass); and a report number you can verify on the issuing lab's own website [5][6].

How to spot a fake or unverifiable COA

Common red flags: no named lab, or one with no verifiable existence; a report number you can't confirm at the lab's site [5]; recycled templates or borrowed logos; identical, suspiciously perfect numbers across every product; lot numbers that don't match the vial, or test dates before manufacture; endotoxin claims with no LAL test, or “purity” presented as if it covered contamination (it doesn't) [7]; and self-testing or supplier-recommended labs. PeptideCheck assesses vendors against exactly these verifiable points.