[Question] is 98.3% actually fine or am I being sold a rounding error
Short version of the title, which is already short: is 98.3% actually fine or am I being sold a rounding error. Longer version underneath.
Since the title puts numbers in the shop window: 98.3%.
Water content 3.8%, acetate 6.2%, purity 99%, net peptide about 90% of label weight. All four numbers honest, and I had to read it twice.
The document I was worried about turned out to be a re-issue with a later creation date. Asked, got the original, entirely ordinary.
Would rather be corrected in public than confident in private.
best — the order this archive was captured in
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.
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.
Does the lot on the vial match the lot on the page?
Your name and address edited out of the screenshot above. The batch details are untouched and should stay.
Yes. The structure of the document matters at least as much as the number printed on it.
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.
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.
That is not what the method line says. It names the technique; it does not certify the operator.
Sent one vial to PeptideMeter and Medutest. 99.2% and a claimed 99.0%. Cost me more than the vial and I would do it again.
Sent one vial to PeptideMeter and Medutest.
katrin_girard has the distinction right — one is a fraction of the detector signal, the other is a fraction of the mass.
katrin_girard has the distinction right — one is a fraction of the detector signal, the other is a fraction of the mass.
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.