an identical chromatogram on two different lots is the single biggest tell there is
#coa-reading 2026-05-30
Saturday16 messages4 participantstimes are UTC
Highlights from this day
- gradient_greg — a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully 10:23
- blank_run — a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists 10:30
- gradient_greg — ok so the honest summary is that a certificate tells you what the supplier says about a lot they chose to test mixed fonts and inconsistent kerning in one document is… 10:33
- blank_run — i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does 10:50
a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully
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not evidence on its own
| 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 |
does anyone keep a folder of certificates to compare over time
a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists
weights-monthly.csv
116 rows · not retained in the public archive
ok so the honest summary is that a certificate tells you what the supplier says about a lot they chose to test
mixed fonts and inconsistent kerning in one document is worth a second look
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certificate is dated before the lot date, is that just sloppiness
is water content normally on a certificate or do you have to ask
check the lot
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not
residual solvents matter more than people think for anything that went through a lot of purification steps
i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does
no lot number on this certificate, does that make it worthless
if you only read one line on a certificate, read the lot number. if you read two, read the assay
thats a real table
is sterility tested as part of a normal purity certificate