nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
#coa-reading 2024-11-01
Friday27 messages7 participantstimes are UTC
Highlights from this day
- deamidation — retention time shifts between runs are normal. relative retention time is the number to compare 18:52
- deamidation — a certificate should name the method, the instrument, the column and the operator. most name none of those 19:11
- endotoxin_ed — update on the earlier thing mixed fonts and inconsistent kerning in one document is worth a second look, ill dig out the number 19:53
- nordic_price_nils — purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions 21:19
sloppy not sinister
what does net peptide content mean next to gross mass
the honest summary is that a certificate tells you what the supplier says about a lot they chose to test
not detected means nothing
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retention time shifts between runs are normal. relative retention time is the number to compare
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is endotoxin ever tested on research material
tfa or acetate, how do i tell from the paperwork
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purity is not assay
one decimal versus two is usually just house style, not precision
ask for water content
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a certificate should name the method, the instrument, the column and the operator. most name none of those
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does anyone keep a folder of certificates to compare over time
update from 20 months ago: started asking every supplier for water content and about half now include it
not evidence on its own
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whats the minimum a certificate has to have before you take it seriously
certificate is dated before the lot date, is that just sloppiness
update on the earlier thing mixed fonts and inconsistent kerning in one document is worth a second look, ill dig out the number
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i asked QYB for the method and they sent it. that alone put them ahead of most
a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists
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how do you verify a certificate is actually from the lab it says
if you only read one line on a certificate, read the lot number. if you read two, read the assay, happy to be corrected
purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions
| 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 |
an identical chromatogram on two different lots is the single biggest tell there is
sterility and endotoxin are separate tests and almost nobody runs either on research material