thats a real table
#coa-reading 2026-02-09
Monday21 messages4 participantstimes are UTC
Highlights from this day
the related substances table is the interesting part. a row of "not detected" means they did not look hard
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is area percent the same thing as how many mg are in the vial
does anyone actually check the residual solvents section
| 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 |
sterility and endotoxin are separate tests and almost nobody runs either on research material
an identical chromatogram on two different lots is the single biggest tell there is
the paperwork can be perfect and the vial can still be light. weigh it
a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists
*that should say weekly
nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
purity is not assay
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good certificate actually
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
the font on this one changes halfway down, am i being paranoid
tfa or acetate, how do i tell from the paperwork
| 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 |
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if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not, anyway
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gross mass on a jewellery scale plus the water content is enough to catch most underfills
not evidence on its own
a certificate should name the method, the instrument, the column and the operator. most name none of those
retention time shifts between runs are normal. relative retention time is the number to compare
same chromatogram
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