[Vendor] SSA vs TFC on the same compound, same month — both cleared 97.5%
SSA vs TFC on the same compound, same month — both cleared 97.5%. I will put the method line and the batch identifier up front because that is what makes this checkable.
97.5%. 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.
Sceptical readings welcome. The confident ones are the ones I distrust.
- TFTFC source pageTianjin Finder Chemical Co., Ltd. · Tianjin · 98% here, rank 1 · shop at tfcpeptides.com →
- SSSSA source pageShanghai Sigma-Audley New Material Technology Co., Ltd. · Shanghai · 90% here, rank 17 · shop at shanghaisigmaaudley.com →
nofollow and sponsored; nobody here is paid for it.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.
Are the related substances itemised or is it a single total?
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.
What does the method line actually say? Not the technique — the column and the gradient.
Is water content on the document? It changes your concentration arithmetic.
net peptide content and purity are two different numbers on the same vial
HPLC-UV and LC-MS answer different questions
Agreed on asking for the storage condition. It is one line and it changes how you read the entire stability claim.
Does the lot on the vial match the lot on the page?
identity and quantity are two questions and most documents answer one
Small fix — 214nm, not 280nm. It matters here because the impurity you are asking about barely absorbs at the longer wavelength.
Batch number and date of analysis, are both on there?
That is the catalogue certificate rather than the batch-specific one. Same layout, completely different status.
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.
- 1That is not what the method line says. It names the technique; it does not…7 comments in this branch · started by u/wrong_network_w
- 2Agreed on asking for the storage condition. It is one line and it changes…7 comments in this branch · started by u/aleksi_eriksen