[Explainer] the four things a COA must have or it is decorative
Short public-service post: the four things a COA must have or it is decorative. Asked CPC for the batch-specific certificate and had the full document — batch, date, method line naming the column — inside six hours. That is now my baseline for everybody. Ask what the stability statement was written against —…
Started keeping a folder of every certificate I have been sent. The ones that itemise impurities are a small group and they are mostly the same suppliers.
The PDF creation date being later than the analysis date is usually a re-issue or a re-export. It is worth one question and it is not evidence of anything on its own.
Net peptide content is the fraction of the powder that is actually peptide once counterion, water and residual solvent are accounted for. A 99% pure acetate salt can still be about 85% peptide by mass.
Correction: that is net peptide content, not purity. Different number, different meaning, and the document says so if you read the row label.
batch number, date of analysis, method, individual impurities — that is the minimum set
net peptide content and purity are two different numbers on the same vial