[Lab] split one vial across VendorInvestigate and PeptideMeter — 97.2% and 96.8%
split one vial across VendorInvestigate and PeptideMeter — 97.2% and 96.8%. One vial, one service, one member paying, which is the only kind of result this board should treat as evidence. Hard numbers: 97.2% and 96.8%. Anything softer than that is flagged as an impression. Spent four months confusing area% and mass%…
Not quite. Two labs with different gradients can resolve a close-eluting impurity differently and both be reporting honestly.
The four things a certificate must carry, and what each one is for.
Batch identifier ties the document to your vial; without it the document is about somebody else’s material. Date of analysis tells you when the number was true. Method — column, gradient, wavelength — is what makes the figure reproducible rather than asserted. Individual related substances give you the shape of what else is in there.
Everything beyond those four is welcome. Anything missing from them is a question to ask before you order, and in my experience the answer arrives quickly from the suppliers who have a batch record to draw it from.
Are the related substances itemised or is it a single total?
Not quite.
This is the sentence to take away. The rest of the thread is footnotes to it.
The document I was worried about turned out to be a re-issue with a later creation date. Asked, got the original, entirely ordinary.
Small fix — 214nm, not 280nm. It matters here because the impurity you are asking about barely absorbs at the longer wavelength.
Not quite.
Agreed, and the practical version is: ask for the itemised table. If it exists, you get it.
Agreed, and the practical version is: ask for the itemised table.
Disagree on this specific point. Two honest labs can resolve that impurity differently and report different numbers.
a certificate with no method line is decorative