nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
#coa-reading 2025-05-23
Friday32 messages8 participantstimes are UTC
Highlights from this day
- point_two_five — noticed something on a cert method, wavelength, column, gradient. a purity number without those is a number someone typed, file it as a pdf 16:59
- area_percent — reading a cert here and how much does the counterion being unstated actually matter 19:21
- perth_pin — update as promised the honest summary is that a certificate tells you what the supplier says about a lot they chose to test, three way match first 20:08
noticed something on a cert method, wavelength, column, gradient. a purity number without those is a number someone typed, file it as a pdf
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residual solvent screens are not standard on peptide certs and are a genuinely good sign when present, that is how i read it anyway
the retyped ones give themselves away on alignment and on the fonts changing mid table
that would explain it
right so what does net peptide content mean next to gross mass
reading one now, so i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does. thats the tell
one decimal versus two is usually just house style, not precision, that is a documentation point not a quality one
batch record instead this time whats the related substances table actually telling me, if anyone has a number
is it a red flag if the certificate is a jpeg rather than a pdf
evening, lot, date, method, wavelength
certificate question the teaching example we use is the one with the populated impurities table and the dated signature, not detected means the limit
Member note: two_three_lifts has logged 3 independent reports.
small thing on the impurity table ask for the batch record by lot code and a serious supplier sends it. that is the whole test, if the method is on it. same chromatogram
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one for the cert readers the three way match is vial, certificate, invoice. if all three agree you have something. ask for the batch record
what does a properly itemised impurity table actually look like, idle question
a chromatogram that does not match the table underneath it is the most common tell i see, filed by year
the impurity table is where the information is. the headline purity is the least interesting number on the page
retention time shifts between runs are normal. relative retention time is the number to compare, email before accusation
a signature block that is a low resolution graphic on a high resolution document is worth noticing, purity is not assay
Member note: point_two_five joined this channel on 2024-07-12 and has 102 messages here.
on net versus gross again purity is a fraction of what is there. assay is how much is there. this channel exists because those get swapped, ok ill stop
pedantry incoming mixed fonts and inconsistent kerning in one document is worth a second look, karl fischer would settle it
harder to fake
anyone compared a supplier certificate against an independent assay on the same lot
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if you only read one line on a certificate, read the lot number. if you read two, read the assay, happy to be corrected by someone who runs these
the paperwork can be perfect and the vial can still be light. weigh it, no date, no story. still uncheckable
[edited]reading a cert here and how much does the counterion being unstated actually matter
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what should a related substances table actually look like when it is done properly
does anyone check whether the chromatogram matches the numbers in the table
what do people do when the certificate and the vial label disagree
evening
single wavelength detection can miss a co-eluting impurity that does not absorb there, nothing here is advice about using any of it. ask for the batch record
update as promised the honest summary is that a certificate tells you what the supplier says about a lot they chose to test, three way match first
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