[COA] full document, nothing cropped, tell me what i am missing
Posting this because the title is the whole finding — full document, nothing cropped, tell me what i am missing — and a number without its method is a rumour.
How to ask for a batch record without it turning into a negotiation.
One email, three requests: the batch-specific certificate for lot X, the method line behind it, and the storage condition the stability statement was written against. No preamble, no explanation of why you want it.
What comes back is the signal. A full document with the column and gradient printed on it, inside a day, tells you there is a real quality system behind the operation. That is the test I run before I order from anyone new, and it costs nothing.
Area percent is the peak area of your compound over the total integrated area, at one wavelength, on one gradient. It is a relative measure of what the detector saw, not a mass fraction of the vial.
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.
Sceptical readings welcome. The confident ones are the ones I distrust.
best — the order this archive was captured in
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.
LC-MS gives you identity; UV purity gives you a relative quantity.
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.
Is water content on the document? It changes your concentration arithmetic.
redact your own name, never the batch details
Not quite. Two labs with different gradients can resolve a close-eluting impurity differently and both be reporting honestly.
post the whole document, not the headline number
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.
identity and quantity are two questions and most documents answer one
identity and quantity are two questions and most documents answer one
This is the sentence to take away. The rest of the thread is footnotes to it.
HPLC-UV and LC-MS answer different questions
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.
Related substances itemised individually is a much stronger document than a single total, because it tells you the shape of the impurity profile rather than its size.
the lot on the vial has to match the lot on the page
Did you get the chromatogram or only the summary line?
a certificate with no method line is decorative
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.
That is the catalogue certificate rather than the batch-specific one. Same layout, completely different status.
net peptide content and purity are two different numbers on the same vial