mixed fonts and inconsistent kerning in one document is worth a second look
🎉15📉6
#coa-reading 2025-09-23
Tuesday31 messages5 participantstimes are UTC
Highlights from this day
- fibre_first — mixed fonts and inconsistent kerning in one document is worth a second look 19:12
- lot_number_lou — if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not 20:10
- lot_number_lou — ok so residual solvents matter more than people think for anything that went through a lot of purification steps 20:44
- lot_number_lou — does anyone keep a folder of certificates to compare over time 21:21
- lot_number_lou — sterility and endotoxin are separate tests and almost nobody runs either on research material, we shall see 21:23
right so the retention time on this one is different from the last lot, problem
❤️5
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
good certificate actually
whats the related substances table actually telling me
test it yourself
| Line | Claims | Does not claim |
|---|---|---|
| Purity (area %) | fraction of detected material that is the target | how many mg are in the vial |
| Assay / content | mg of target per vial | that it is sterile |
| Water content | mass fraction that is water | anything about purity |
| Counterion | salt form and its mass share | net peptide unless stated |
| Related substances | what else was seen | what was not looked for |
no lot number on this certificate, does that make it worthless
tfa counterion runs higher by mass than acetate. if the certificate does not say, you cannot do the mass balance
the honest summary is that a certificate tells you what the supplier says about a lot they chose to test
i keep every certificate in a dated folder and compare them. two suppliers had not changed their template since 2019
a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully
why would a vial be 99.2 pure and still assay under label
coming back after 23 months, has the pinned reading guide changed
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not
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 / 10mgthe three way match is vial, certificate, invoice. if all three agree you have something
[edited]no lot no certificate
⚠️2✅12
20:33ferrous_ash pinned a message to this channel
single wavelength detection can miss a co-eluting impurity that does not absorb there
net not gross
update on the earlier thing an identical chromatogram on two different lots is the single biggest tell there is
📈3
ok so residual solvents matter more than people think for anything that went through a lot of purification steps
🎉1🧊5
i asked SSA for the method and they sent it. that alone put them ahead of most
does purity by hplc at one wavelength miss things
not detected means nothing
📈3
thats a tell
does anyone keep a folder of certificates to compare over time
🤝8
sterility and endotoxin are separate tests and almost nobody runs either on research material, we shall see
🤝1⚠️9🧪4
sloppy not sinister
thats a real table