Identifying Information
The top section of a certificate of analysis should clearly identify the product name, catalog or lot number, batch or lot number specific to the physical material received, manufacturing date, and, where applicable, retest or expiry date. Buyers should confirm that the batch number listed on the certificate matches the batch number on the physical product label, since a mismatch, even an apparently minor one, indicates a documentation error that should be resolved with the manufacturer before the material is used.
The certificate should also identify the specific manufacturing facility, particularly relevant for manufacturers operating multiple sites, since certification and regulatory status can differ between facilities even within the same company.
Purity and Identity Data
The HPLC purity result should be presented as a specific percentage along with the test method or reference to a validated method, and ideally the actual chromatogram or a summary of key retention time and peak area data rather than only the final percentage. The molecular weight, confirmed by mass spectrometry, should match the theoretical molecular weight calculated from the peptide’s sequence, and any deviation should be explained rather than simply reported without context.
Buyers should independently calculate or verify the expected molecular weight for the sequence when feasible, as a straightforward cross-check against the reported value on the certificate.
Additional Quality Parameters
Depending on the peptide grade, the certificate should also report parameters such as residual solvent content, water content or moisture level (particularly relevant for lyophilized material, where it affects both stability and accurate potency calculations), counter-ion content for peptides supplied as a salt form, and, for pharmaceutical-grade material, microbial limits and endotoxin testing where relevant to the intended use.
Any parameter listed as ‘not tested’ or left blank should prompt a direct question to the manufacturer about why that testing was not performed and whether it is available on request, particularly for parameters relevant to the buyer’s specific regulatory requirements.
Signatures, Approval, and Document Integrity
A legitimate certificate of analysis should include a signature or formal approval from the manufacturer’s quality assurance function, not only the analyst who performed testing, reflecting an independent quality review of the results before release. Buyers should be alert to certificates that appear to be templates with only the batch number changed, rather than documents reflecting genuine batch-specific testing, and should not hesitate to ask the manufacturer directly for the underlying raw data if a certificate raises any doubt.
Retaining certificates of analysis systematically, organized by batch and cross-referenced to physical inventory, supports both routine quality management and any future investigation that may require tracing a specific batch’s documented quality history.