Reading your first COA.

This is identity. The name says what the molecule is called; the CAS number is the international registry ID for that exact molecule (no two compounds share a CAS); the molecular formula and molecular weight describe the structure. If any of these four lines does not match what is on the product page you ordered, stop — that is a packaging or paperwork mismatch and we want to know about it.

This is provenance. The batch number ties the COA to a specific synthesis run. The manufacture date is when the powder was made; the retest date is when the lab recommends re-analysing the material to confirm continued purity. Lyophilized peptides typically carry a two-year retest window when stored correctly. The batch number on this certificate must match the batch printed on the vial label.

What the powder looks like. “White lyophilized powder” or “off-white lyophilized cake” are typical. If the vial you receive contains a cracked, melted or yellow-stained cake, document with a photo before reconstitution and contact support — that is usually a transit-temperature issue, not a content issue, but we still want the photo.

The headline purity number. 99.13 % means that of all the molecules detected by the chromatography, 99.13 % were the intended peptide. The remaining 0.87 % are typically synthesis side-products or fragments — not contamination from a different compound. Reputable COAs include the chromatogram (a graph of detector peaks); if the certificate is missing the picture, ask for it.

Mass spectrometry confirms that the molecule has the mass it should. “M+H” is the molecule plus one hydrogen ion (the standard ionisation in positive-mode MS). 1420.51 matches the expected molecular weight (1419.53) plus a hydrogen, so the structure is confirmed. A purity test alone could be high while still measuring the wrong molecule; mass spec rules that out.

How much residual water is left in the lyophilized cake. Single-digit percentages are normal; very high values (> 10 %) indicate poor freeze-drying. Karl-Fischer is the analytical method — a titration that specifically reacts with water.

Most peptides ship as acetate salts (a chemistry artefact of the synthesis purification). The acetate contributes to the total weight in the vial — a 5 mg vial of “BPC-157 acetate” with 8.6 % acetate contains 5 mg of total powder, of which roughly 4.57 mg is the active peptide and 0.43 mg is acetate. Whether the labelled mass refers to peptide-base or salt-form is a question worth asking; this catalog labels by the salt form (total powder).

Endotoxins are fragments of bacterial cell walls. The test is reported in EU/mg (Endotoxin Units per milligram). Low single-digit values are typical for research-grade material that has not been processed under sterile (pharmaceutical) conditions. This is a research test, not a sterility certification.

A COA is a signed document. The signature line attributes the certificate to a specific QC analyst at the testing lab. Unsigned COAs are unfinished paperwork.