[PSA] purity is not what most of this community thinks it is
purity is not what most of this community thinks it is. Two minutes of reading now saves an argument later. My first certificate had a compound name, a percentage and a logo. I thought that was normal. It is not, and now I know what to ask for. How to ask for a batch record without it turning into a negotiation. One…
Did you get the chromatogram or only the summary line?
Sent one vial to Medutest and PeptideMeter. 98.8% and a claimed 98.0%. Cost me more than the vial and I would do it again.
a total of 0.4% tells you less than four named impurities adding to 0.6%
ask for the storage condition the stability statement was written against
HPLC-UV and LC-MS answer different questions
HPLC-UV and LC-MS answer different questions
Disagree on this specific point. Two honest labs can resolve that impurity differently and report different numbers.
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.
Yes — and the reason to ask for the whole page is that the interesting parts are the ones people crop out to fit a screenshot.