COA — 5 things I got wrong before I got it right
COA — 5 things I got wrong before I got it right — a position I have arrived at slowly and would like tested.
LC-MS gives you identity; UV purity gives you a relative quantity. A document with the first and not the second, or the reverse, is answering half the question.
Asked ERP 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.
Sent one vial to Medutest and Janoshik. 99.1% and a claimed 98.5%. Cost me more than the vial and I would do it again.
Research-use-only material is not approved for human use and nothing here should be read as a recommendation to use it.
best — the order this archive was captured in
Ask what the stability statement was written against — temperature, light, and whether it was the lyophilised powder or the reconstituted solution. Those are three different claims.
Reminder: a question about a document is not an accusation about a supplier, and posts that blur the two get retitled.
The document I was worried about turned out to be a re-issue with a later creation date. Asked, got the original, entirely ordinary.
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.
Area percent or net peptide content? They answer different questions.