how do i tell an HPLC-UV COA from an LC-MS one at a glance
Slightly embarrassed to be asking this, but: how do i tell an HPLC-UV COA from an LC-MS one at a glance. 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…
UV at 214nm sees the peptide bond and picks up almost everything; at 280nm you are looking at aromatics only. Which wavelength the number came from is part of the number.
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.
Small fix — 214nm, not 280nm. It matters here because the impurity you are asking about barely absorbs at the longer wavelength.
chromatogram or it did not happen
chromatogram or it did not happen
Adding the bit that always gets missed: the lot on the vial has to match the lot on the page, or none of this applies to your material.
axis labels included, always
Not quite. Two labs with different gradients can resolve a close-eluting impurity differently and both be reporting honestly.