What tests should a peptide COA include?

Question, test, limit

Pharmacopoeia chapters such as USP <621>, <85> and <71> are paywalled, so this page cites free regulator documents and does not reproduce those chapters.

• Is it the named compound? Identity: mass spectrometry for molecular mass and sequence, retention time, LC-MS or peptide mapping (EMA). It does not by itself show how much peptide is present or whether the sample is sterile.
• How much other material is in it? Purity and impurities, controlled as total and individual impurities (EMA). The result depends on the method used, and it is not an amount per vial.
• How much peptide is in it? Assay by liquid chromatography, amino acid analysis, nitrogen analysis or qNMR, on a counter-ion-free, anhydrous basis (EMA). It needs a reference standard.
• What else is in the powder? Water content and counter-ion content (EMA). They explain why content is below total weight, by our inference.
• Were manufacturing solvents left behind? Residual solvents under ICH Q3C, in three classes. A COA that lists none has not reported on them.
• Were metals tested? Elemental impurities under ICH Q3D, which sets permitted daily exposures for 24 elements.
• Was endotoxin measured? Bacterial endotoxin testing by gel-clot, photometric or kinetic methods (FDA Q&A). Check the method and the stated limit.
• Was it tested for sterility? A separate test. 21 CFR 211.167(a) requires testing for products purporting to be sterile or pyrogen-free, and FDA's aseptic-processing guidance says sterilizing filters and moist heat have not been shown to remove endotoxin. Our inference: a sterility result does not cover endotoxin, and an endotoxin result does not show sterility.

Limits of any test list

• A COA for a bulk peptide describes that material. A filled vial needs its own results.
• More tests do not make a document authentic. See our verification guide.
• We do not give a purity or endotoxin value that counts as acceptable. Those depend on the product and use, and an analytical specialist should set them.
• A complete COA would not make a product legal to sell or fit for human use. See our research-use-only explainer.