coming back after 15 months, has the pinned reading guide changed
i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does
#coa-reading 2026-03-07
Saturday38 messages7 participantstimes are UTC
Highlights from this day
- peak_split — nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself 22:41
- courier_vs_post — the certificate from GGPeps is the one i use to teach this because it actually has a populated impurity table 22:54
- nettle_notes — is sterility tested as part of a normal purity certificate 23:00
- nettle_notes — ok so gross mass on a jewellery scale plus the water content is enough to catch most underfills, n of 1 obviously 23:37
- nettle_notes — i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does, take that with a pinch of salt 23:45
net not gross
thats a real table
purity is not assay
why do some certificates report to one decimal and some to two
nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
🎉14
whats the minimum a certificate has to have before you take it seriously
whats the related substances table actually telling me
ok so no lot number on this certificate, does that make it worthless
test it yourself
check the lot
no lot no certificate
not detected means nothing
sloppy not sinister
the certificate from GGPeps is the one i use to teach this because it actually has a populated impurity table
should a certificate say which instrument and method they used
i keep every certificate in a dated folder and compare them. two suppliers had not changed their template since 2019, someone check my working
is sterility tested as part of a normal purity certificate
💀1👍9😂6
a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully, i think
*that should say weekly
thats a tell
*that should say weekly
weigh the vial
[edited]*VendorInvestigate not the other one
thats the counterion
not evidence on its own
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
follow up one decimal versus two is usually just house style, not precision
the retention time on this one is different from the last lot, problem
purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions
i asked BCH for the method and they sent it. that alone put them ahead of most
looks re-dated
an identical chromatogram on two different lots is the single biggest tell there is, thats one data point
net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial
ok so gross mass on a jewellery scale plus the water content is enough to catch most underfills, n of 1 obviously
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
i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does, take that with a pinch of salt
[edited]🎉8💀7✅1
water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it