the paperwork can be perfect and the vial can still be light. weigh it, from memory
#coa-reading 2025-10-02
Thursday32 messages7 participantstimes are UTC
Highlights from this day
- HPLC_Hank — sorry to jump in one decimal versus two is usually just house style, not precision a supplier certificate on its own is a starting point, not evidence. that is the… 21:06
- warsaw_vial — update from 16 months ago: started asking every supplier for water content and about half now include it 22:09
- peak_split — mixed fonts and inconsistent kerning in one document is worth a second look 22:39
- peak_split — the related substances table is the interesting part. a row of "not detected" means they did not look hard 23:03
- peak_split — purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions 23:17
coming back to this whats the related substances table actually telling me
the font on this one changes halfway down, am i being paranoid
the three way match is vial, certificate, invoice. if all three agree you have something
should a certificate say which instrument and method they used
[edited]single wavelength detection can miss a co-eluting impurity that does not absorb there, ask me again in a month
thats a real table
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net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial
sorry to jump in one decimal versus two is usually just house style, not precision
a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists
ask for water content
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not
nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself, someone check my working
purity is not assay
a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully
does anyone keep a folder of certificates to compare over time
coming back to this an identical chromatogram on two different lots is the single biggest tell there is
cat_on_the_traya lab that reports "greater than 98%" rather than a number is telling you they did not…
the retention time on this one is different from the last lot, problem
a certificate should name the method, the instrument, the column and the operator. most name none of those
residual solvents matter more than people think for anything that went through a lot of purification steps
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update from 16 months ago: started asking every supplier for water content and about half now include it
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no lot number, no certificate. a document you cannot tie to the vial in your hand is decoration
[edited]the honest summary is that a certificate tells you what the supplier says about a lot they chose to test
seizure_letterthe three way match is vial, certificate, invoice. if all three agree you have something
ok so two certificates from the same supplier have an identical chromatogram, is that normal
water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it
i have never seen a research certificate with an endotoxin result on it. not once
mixed fonts and inconsistent kerning in one document is worth a second look
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net not gross
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the related substances table is the interesting part. a row of "not detected" means they did not look hard
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is sterility tested as part of a normal purity certificate
purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions
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how do you verify a certificate is actually from the lab it says
not evidence on its own