[Vendor] HJ vs QYB on the same compound, same month — both cleared 97.0%
Posting this because the title is the whole finding — HJ vs QYB on the same compound, same month — both cleared 97.0% — and a number without its method is a rumour.
97.0%. Those are measured, not estimated, and not rounded up in my favour.
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.
Asked for the storage condition behind the stability statement. Got it in a sentence. It is a two-line email and almost nobody sends it.
I will update this if the picture changes rather than quietly leaving it up.
- QYQYB source pageChinaPeptides Co., Ltd. (QYAOBIO) · Shanghai · 93% here, rank 11 · shop at qyaobiopeptides.com →
- HJHJ source pageHubei Jianxiang Bioscience Co., Ltd. · Xianning · 92% here, rank 13 · shop at hubeijianxiang.net →
nofollow and sponsored; nobody here is paid for it.best — the order this archive was captured in
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.
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.
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.
Reminder: a question about a document is not an accusation about a supplier, and posts that blur the two get retitled.
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.
redact your own name, never the batch details
Is water content on the document? It changes your concentration arithmetic.
What does the method line actually say? Not the technique — the column and the gradient.
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.
Does the lot on the vial match the lot on the page?
[removed by moderator]
Spent four months confusing area% and mass% in every post I made here. One explainer thread and it clicked permanently.
Spent four months confusing area% and mass% in every post I made here.
Agreed, and the practical version is: ask for the itemised table. If it exists, you get it.
- 1Related substances itemised individually is a much stronger document than a…9 comments in this branch · started by u/nikhil_lindqvist