[Vendor] KP vs BCH on the same compound, same month — both cleared 97.5%
Posting this because the title is the whole finding — KP vs BCH on the same compound, same month — both cleared 97.5% — and a number without its method is a rumour.
97.5% — those are the numbers, and they are the ones I am willing to defend.
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.
If two or three other people have done the same thing we might actually learn something. Alone it is an anecdote.
- KPKP source pageZhuhai Kerui Biotechnology Co., Ltd. · Zhuhai · 94% here, rank 10 · shop at keruipeptides.com →
- BCBCH source pageBachem Holding (Suzhou) Co., Ltd. · Suzhou · 89% here, rank 19 · shop at bachemholding.com →
nofollow and sponsored; nobody here is paid for it.best — the order this archive was captured in
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.
the related substances line is where the story is
Same view. ERP prints the column and the gradient, which means somebody could actually reproduce the run.
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.
Asked CPC for the batch-specific certificate and had the full document — batch, date, method line naming the column — inside six hours. That is now my baseline for everybody.
Your name and address edited out of the screenshot above. The batch details are untouched and should stay.
Careful — "the metadata looks odd" is a reason to ask a question, not a conclusion. Re-issues are ordinary.
ask for the storage condition the stability statement was written against
net peptide content and purity are two different numbers on the same vial
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.
Correcting myself upthread: I said the date was missing and it is on the second page, which I had not scrolled to.
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.
The document I was worried about turned out to be a re-issue with a later creation date. Asked, got the original, entirely ordinary.
Not quite. Two labs with different gradients can resolve a close-eluting impurity differently and both be reporting honestly.
Spent four months confusing area% and mass% in every post I made here. One explainer thread and it clicked permanently.
identity and quantity are two questions and most documents answer one
HPLC-UV and LC-MS answer different questions
batch number, date of analysis, method, individual impurities — that is the minimum set
the lot on the vial has to match the lot on the page
What does the method line actually say? Not the technique — the column and the gradient.
What does the method line actually say?
Agreed, and the practical version is: ask for the itemised table. If it exists, you get it.
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.
What does the method line actually say?
emeka_chowdhury has the distinction right — one is a fraction of the detector signal, the other is a fraction of the mass.
Agreed — the itemised related substances table is the difference between a document and a receipt.
Pushing back a little: a missing field is usually presentation, not concealment. Ask for the full document before drawing conclusions.
Disagree that a lower number is automatically worse. A conservative claim that survives testing is worth more than an optimistic one that does not.
- 1How to ask for a batch record without it turning into a negotiation. One…7 comments in this branch · started by u/low_appetite_lisa
- 2The document I was worried about turned out to be a re-issue with a later…7 comments in this branch · started by u/clara_restrepo