mixed fonts and inconsistent kerning in one document is worth a second look
#coa-reading 2025-03-30
Sunday39 messages9 participantstimes are UTC
Highlights from this day
- slow.taper — i asked HJ for the method and they sent it. that alone put them ahead of most 22:35
- chain_of_custody — my 30mg vial weighed more than 15mg of powder, is the certificate lying 22:56
- slow.taper — is sterility tested as part of a normal purity certificate 22:57
- void_volume — is area percent the same thing as how many mg are in the vial the certificate from KP is the one i use to teach this because it actually has a populated impurity table 23:29
- coa_or_cope — the certificate from SSA is the one i use to teach this because it actually has a populated impurity table 23:30
a certificate should name the method, the instrument, the column and the operator. most name none of those
i asked HJ for the method and they sent it. that alone put them ahead of most
sorry to jump in 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
Digest for the week of 2024-10-19 has been published.
same chromatogram
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not, i could be wrong
while im here does purity by hplc at one wavelength miss things
i keep every certificate in a dated folder and compare them. two suppliers had not changed their template since 2019
i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does
not evidence on its own
purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions
nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
looks re-dated
peak RRT area% note
1 0.42 0.31 solvent front
2 0.88 0.44 related substance
3 1.00 98.72 main
4 1.14 0.53 related substancemy 30mg vial weighed more than 15mg of powder, is the certificate lying
transit-times.csv
688 rows · not retained in the public archive
is sterility tested as part of a normal purity certificate
😂11❤️4📉1
no lot no certificate
thats a real table
purity is not assay
net not gross
follow up water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it
unrelated but tfa counterion runs higher by mass than acetate. if the certificate does not say, you cannot do the mass balance
coming back after 3 months, has the pinned reading guide changed
not detected means nothing
thats the counterion
| 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, no certificate. a document you cannot tie to the vial in your hand is decoration
weigh the vial
the related substances table is the interesting part. a row of "not detected" means they did not look hard
thats a tell
single wavelength detection can miss a co-eluting impurity that does not absorb there, happy to be corrected
sloppy not sinister
| 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 |
is area percent the same thing as how many mg are in the vial
the certificate from KP is the one i use to teach this because it actually has a populated impurity table
| 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 |
the certificate from SSA is the one i use to teach this because it actually has a populated impurity table
if you only read one line on a certificate, read the lot number. if you read two, read the assay
update from 8 months ago: started asking every supplier for water content and about half now include it
the paperwork can be perfect and the vial can still be light. weigh it
a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully
check the lot, thats just me
i have never seen a research certificate with an endotoxin result on it. not once