What a peptide certificate of analysis should actually include
A certificate of analysis is a lab's statement that a specific lot met a written specification. Anything that doesn't name the lot, the tests and the results is not a CoA. Here is what to expect on a peptide CoA from a supplier who intends to stand behind it.
Identifiers
- Product name and sequence or CAS reference
- Lot or batch number matching the vial label
- Manufacture date and retest or expiry date
- Issuing lab and a signature or approval
Purity
Purity by analytical HPLC, reported as a percentage with the method named (column, gradient, detection wavelength). A specification of at least 99% is standard for pharmacy-grade material. Ask to see the chromatogram; a single clean peak with small, identified impurities is what you want.
Identity
Mass spectrometry (LC-MS or MALDI) confirming the observed mass matches the theoretical mass of the sequence. Purity without identity means a very pure sample of something; identity is what tells you it's the right something.
Content
Net peptide content on bulk API, because lyophilized peptides carry water and counter-ion (acetate or TFA). A 10 mg vial that is 85% net peptide contains 8.5 mg of peptide. Pharmacies need this number to compound accurately.
Safety tests on injectable-grade vials
- Bacterial endotoxin (LAL), typically reported in EU/mg
- Sterility per USP <71>
- Water content by Karl Fischer on bulk
- Residual solvents where relevant
What a marketing sheet looks like
No lot number. "Purity: 99%+" with no method. The same PDF for every batch. A logo but no lab. If your current supplier's documents match that description, you are carrying the risk they should be carrying.
Every lot we ship carries a CoA built to this list. Request a sample.