slightly off topic but if you only read one line on a certificate, read the lot number. if you read two, read the assay
#coa-reading 2025-05-17
Saturday14 messages3 participantstimes are UTC
Highlights from this day
a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully
one decimal versus two is usually just house style, not precision
| 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 |
good certificate actually
for the archive what does net peptide content mean next to gross mass
nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
the paperwork can be perfect and the vial can still be light. weigh it
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the three way match is vial, certificate, invoice. if all three agree you have something
gross mass on a jewellery scale plus the water content is enough to catch most underfills, from memory
ok so two certificates from the same supplier have an identical chromatogram, is that normal
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 certificate from QST is the one i use to teach this because it actually has a populated impurity table, i could be wrong
no lot no certificate
thats a real table
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an identical chromatogram on two different lots is the single biggest tell there is
if you only read one line on a certificate, read the lot number. if you read two, read the assay