nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
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#coa-reading 2026-01-13
Tuesday39 messages7 participantstimes are UTC
Highlights from this day
- acetate_ash — nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself 09:50
- swab_dry_first — the certificate from BCH is the one i use to teach this because it actually has a populated impurity table, i could be wrong 11:05
- peak_split — one decimal versus two is usually just house style, not precision 11:47
- peak_split — i have never seen a research certificate with an endotoxin result on it. not once 13:04
the paperwork can be perfect and the vial can still be light. weigh it
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is water content normally on a certificate or do you have to ask
no lot no certificate
not detected means nothing
residual solvents matter more than people think for anything that went through a lot of purification steps, i think
a vial can be 99.4% pure and hold 8.1mg of a 10mg label. both numbers are true and only one of them is the one you care about
i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does
whats the minimum a certificate has to have before you take it seriously
medutest-report-sg-1177.pdf
3 pages · 677 KB · not retained in the public archive
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not, thats just me
retention time shifts between runs are normal. relative retention time is the number to compare, take that with a pinch of salt
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sloppy not sinister
purity is not assay
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does anyone actually check the residual solvents section
how do you verify a certificate is actually from the lab it says
why would a vial be 99.2 pure and still assay under label
unrelated but whats the related substances table actually telling me
slightly off topic but purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions
the certificate from BCH is the one i use to teach this because it actually has a populated impurity table, i could be wrong
lot bought purity assay/label
A-2418 2025-03 99.1% 9.6 / 10mg
A-2601 2025-08 98.7% 9.8 / 10mg
B-0114 2026-01 99.3% 9.4 / 10mg
B-0329 2026-04 98.9% 9.9 / 10mgsame chromatogram
one decimal versus two is usually just house style, not precision
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quick one i asked GL Biochem for the method and they sent it. that alone put them ahead of most
*VendorInvestigate not the other one
thats a tell
thats the counterion
water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it
the font on this one changes halfway down, am i being paranoid
sterility and endotoxin are separate tests and almost nobody runs either on research material
the three way match is vial, certificate, invoice. if all three agree you have something
net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial, n of 1 obviously
ask for water content
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is area percent the same thing as how many mg are in the vial
i have never seen a research certificate with an endotoxin result on it. not once
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gross mass on a jewellery scale plus the water content is enough to catch most underfills
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is there a standard layout or does every lab do their own
[edited]coming back after 15 months, has the pinned reading guide changed
certificate is dated before the lot date, is that just sloppiness
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should a certificate say which instrument and method they used
good certificate actually
my 30mg vial weighed more than 2mg of powder, is the certificate lying