why do some certificates report to one decimal and some to two
#coa-reading 2026-03-14
Saturday28 messages7 participantstimes are UTC
Highlights from this day
- VialBot — Batch lookup A-2418: 4 independent reports on file, earliest 2026-01-27. 17:27
- acetate_ash — mixed fonts and inconsistent kerning in one document is worth a second look the paperwork can be perfect and the vial can still be light. weigh it 18:28
- adelaide_assay — 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, thats one data point 20:10
- VialBot — Testing queue: 6 submissions open, 54 awaiting dispatch. 20:13
Batch lookup A-2418: 4 independent reports on file, earliest 2026-01-27.
retention time shifts between runs are normal. relative retention time is the number to compare
*PeptideMeter not the other one
while im here a certificate should name the method, the instrument, the column and the operator. most name none of those
not detected means nothing
sloppy not sinister
looks re-dated
tfa counterion runs higher by mass than acetate. if the certificate does not say, you cannot do the mass balance
how do you verify a certificate is actually from the lab it says
[edited]is sterility tested as part of a normal purity certificate
mixed fonts and inconsistent kerning in one document is worth a second look
the paperwork can be perfect and the vial can still be light. weigh it
purity is not assay
a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists, i could be wrong
[edited]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
good certificate actually
✅3
coming back to this purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions
thats a real table
single wavelength detection can miss a co-eluting impurity that does not absorb there
[edited]a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully
[edited]i have never seen a research certificate with an endotoxin result on it. not once
i keep every certificate in a dated folder and compare them. two suppliers had not changed their template since 2019
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, thats one data point
Testing queue: 6 submissions open, 54 awaiting dispatch.
i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does
thats the counterion
the related substances table is the interesting part. a row of "not detected" means they did not look hard