[Lab] 6th independent test on HJ — 99.1% on a claimed 99.0%, and the trend is the interesting part
6th independent test on HJ — 99.1% on a claimed 99.0%, and the trend is the interesting part. One vial, one service, one member paying, which is the only kind of result this board should treat as evidence.
The relevant figures are 99.1% and 99.0%, and they come from the same log I have kept the whole time.
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.
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.
Please do not ask me what dose you should be on. I genuinely do not know and neither does anyone else here.
- 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
The PDF creation date being later than the analysis date is usually a re-issue or a re-export. It is worth one question and it is not evidence of anything on its own.
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.
Not quite. Two labs with different gradients can resolve a close-eluting impurity differently and both be reporting honestly.
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.
Left up and flaired Explainer. This is the answer we keep linking, written properly.
Correction: that is net peptide content, not purity. Different number, different meaning, and the document says so if you read the row label.
HPLC-UV and LC-MS answer different questions
Disagree that a lower number is automatically worse. A conservative claim that survives testing is worth more than an optimistic one that does not.
This. Area percent answers "what fraction of what the detector saw was the peak I wanted", and people read it as "how much peptide is in the vial".
the lot on the vial has to match the lot on the page
Agreed on asking for the storage condition. It is one line and it changes how you read the entire stability claim.
Sent one vial to VendorInvestigate and Janoshik. 99.0% and a claimed 98.5%. Cost me more than the vial and I would do it again.
Agreed — the itemised related substances table is the difference between a document and a receipt.
Yes — and the reason to ask for the whole page is that the interesting parts are the ones people crop out to fit a screenshot.
the related substances line is where the story is
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.
Did you ask for the batch-specific document, or is this the catalogue one?
Right, and net peptide content is where the counterion and the water go. Both numbers can be honest and very different.
Does the lot on the vial match the lot on the page?
redact your own name, never the batch details
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.
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.
Small fix — 214nm, not 280nm. It matters here because the impurity you are asking about barely absorbs at the longer wavelength.
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.
Batch number and date of analysis, are both on there?
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.
batch number, date of analysis, method, individual impurities — that is the minimum set
- 1Left up and flaired Explainer. This is the answer we keep linking, written…8 comments in this branch · started by u/coa_collector