What Is a Certificate of Analysis?
A Certificate of Analysis (COA) is a document issued by a testing laboratory that reports the analytical test results for a specific batch of a compound. For research peptides, a proper COA should contain: the identity of the compound confirmed by mass spectrometry, the purity by HPLC, the batch or lot number, the testing date, and the laboratory's accreditation credentials. A COA without all of these elements is incomplete at best, fabricated at worst.
HPLC Purity: What the Percentage Actually Means
HPLC (high-performance liquid chromatography) separates a sample's components by molecular properties and produces a chromatogram — a graph of peaks over time. Each peak corresponds to a compound eluting off the column. The "purity percentage" is the area of the target peptide's peak expressed as a fraction of all peak areas. A result of 99.2% means 99.2% of the UV-absorbing material in the sample elutes at the correct retention time for that peptide. What this does NOT tell you: whether that 99.2% peak is actually the right compound, what the remaining mass balance is (water, TFA, mannitol), or whether the sample contains endotoxins.
Mass Spectrometry: The Identity Confirmation
Mass spectrometry determines the molecular weight of compounds in a sample. For peptides, electrospray ionization MS (ESI-MS) or LC-MS/MS confirms the molecular ion matches the expected mass for the correct peptide sequence. This is the only way to confirm identity — HPLC cannot distinguish between two peptides of similar size that coelute at similar retention times. A COA without MS data can confirm purity of something, but cannot confirm it's the right something. Always require MS identity data.
Batch / Lot Number: Why It Must Match
A batch-specific COA means the testing was performed on the exact production lot in your vial. The lot number on the COA must match the lot number on your vial or packaging. A COA without a lot number, or with a lot number that cannot be traced to your order, may be a recycled document from a different (possibly higher-quality) batch applied to your order. This is a common fraud vector in the peptide market.
How to Spot a Fabricated COA
Common signs of a fabricated or manipulated COA: (1) The lab name is not findable in any accreditation database (check A2LA, NVLAP, or ILAC MRA member databases). (2) The chromatogram image is blurry, low-resolution, or looks like a screenshot rather than a PDF export from lab software. (3) The molecular weight in the MS section does not match the known MW for the compound claimed. (4) There is no lot number, or the lot number is a generic placeholder like "LOT001". (5) The document lacks a digital signature or the lab's letterhead cannot be verified via the lab's own website. (6) All COAs from a vendor look suspiciously identical — same peak shape, same baseline noise, only the compound name changed.
What a Genuine Valence Grade COA Includes
Every batch we test includes: HPLC chromatogram with peak area integration table, ESI-MS identity confirmation with the observed and theoretical molecular ion, batch-specific lot number traceable to your order, testing date within the production run, and the issuing lab's ISO 17025 accreditation certificate number. COAs are publicly accessible without login at our COA Library.