no lot number, no certificate. a document you cannot tie to the vial in your hand is decoration
#coa-reading 2026-03-21
Saturday34 messages7 participantstimes are UTC
Highlights from this day
- area_percent — how do you verify a certificate is actually from the lab it says 12:07
- a1c_lag — retention time shifts between runs are normal. relative retention time is the number to compare 12:32
- pharmac_pen — 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 14:51
- no_appetite_nia — a certificate should name the method, the instrument, the column and the operator. most name none of those 15:36
nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
good certificate actually
not detected means nothing
net not gross
test it yourself
if you only read one line on a certificate, read the lot number. if you read two, read the assay
how do you verify a certificate is actually from the lab it says
vial-g-0641-front.png
900 × 1200 · 645 KB · not retained in the public archive
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sterility and endotoxin are separate tests and almost nobody runs either on research material
thats a real table
follow up whats the related substances table actually telling me
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the font on this one changes halfway down, am i being paranoid
a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully, ymmv
does purity by hplc at one wavelength miss things
retention time shifts between runs are normal. relative retention time is the number to compare
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purity is not assay
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the honest summary is that a certificate tells you what the supplier says about a lot they chose to test
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sorry to jump in an identical chromatogram on two different lots is the single biggest tell there is
looks re-dated
check the lot
| 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 |
same chromatogram
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not, we shall see
no lot no certificate
the paperwork can be perfect and the vial can still be light. weigh it
sloppy not sinister
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
janoshik-kp-0925.pdf
2 pages · 830 KB · not retained in the public archive
thats a tell
not evidence on its own
is area percent the same thing as how many mg are in the vial
the related substances table is the interesting part. a row of "not detected" means they did not look hard
ask for water content
mixed fonts and inconsistent kerning in one document is worth a second look
a certificate should name the method, the instrument, the column and the operator. most name none of those
[edited]