the paperwork can be perfect and the vial can still be light. weigh it, not advice obviously
#coa-reading 2025-11-10
Monday37 messages8 participantstimes are UTC
Highlights from this day
- first_and_last_four — the three way match is vial, certificate, invoice. if all three agree you have something 15:57
- logrotate — update from 3 months ago: started asking every supplier for water content and about half now include it 18:40
- taper_or_not — the retention time on this one is different from the last lot, problem no lot number, no certificate. a document you cannot tie to the vial in your hand is decoration 18:48
- VialBot — Recon calculator: 30mg in 0.5ml = 2mg/ml. 22:24
no lot number on this certificate, does that make it worthless
water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it
how do you verify a certificate is actually from the lab it says
update on the earlier thing is endotoxin ever tested on research material
the three way match is vial, certificate, invoice. if all three agree you have something
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mixed fonts and inconsistent kerning in one document is worth a second look, still working it out
thats a tell
a certificate should name the method, the instrument, the column and the operator. most name none of those
does anyone keep a folder of certificates to compare over time
tfa or acetate, how do i tell from the paperwork
nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
whats the minimum a certificate has to have before you take it seriously
what does net peptide content mean next to gross mass
not detected means nothing
is there a standard layout or does every lab do their own
should a certificate say which instrument and method they used
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
test it yourself
if you only read one line on a certificate, read the lot number. if you read two, read the assay
[edited]while im here 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
coming back after 10 months, has the pinned reading guide changed
gross mass on a jewellery scale plus the water content is enough to catch most underfills
is area percent the same thing as how many mg are in the vial
update from 3 months ago: started asking every supplier for water content and about half now include it
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residual solvents matter more than people think for anything that went through a lot of purification steps
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the retention time on this one is different from the last lot, problem
no lot number, no certificate. a document you cannot tie to the vial in your hand is decoration
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good certificate actually
i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does
is a supplier certificate worth anything on its own
sorry to jump in tfa counterion runs higher by mass than acetate. if the certificate does not say, you cannot do the mass balance, thats one data point
update on the earlier thing the related substances table is the interesting part. a row of "not detected" means they did not look hard
i keep every certificate in a dated folder and compare them. two suppliers had not changed their template since 2019
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not, we shall see
one decimal versus two is usually just house style, not precision
Recon calculator: 30mg in 0.5ml = 2mg/ml.
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