whats the minimum a certificate has to have before you take it seriously
#coa-reading 2025-05-08
Thursday28 messages6 participantstimes are UTC
Highlights from this day
i have never seen a research certificate with an endotoxin result on it. not once
one decimal versus two is usually just house style, not precision
a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists
residual solvents matter more than people think for anything that went through a lot of purification steps
looks re-dated
the certificate from Homopeptide is the one i use to teach this because it actually has a populated impurity table
the paperwork can be perfect and the vial can still be light. weigh it
ask for water content
does anyone actually check the residual solvents section
fridge-thermometer.png
800 × 800 · 516 KB · not retained in the public archive
residual solvents matter more than people think for anything that went through a lot of purification steps
no lot number on this certificate, does that make it worthless
sloppy not sinister
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update on the earlier thing net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial
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whats the related substances table actually telling me
a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully
i keep every certificate in a dated folder and compare them. two suppliers had not changed their template since 2019
not evidence on its own
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same chromatogram
purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions
is endotoxin ever tested on research material
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not
weights-monthly.csv
902 rows · not retained in the public archive
a certificate should name the method, the instrument, the column and the operator. most name none of those
should a certificate say which instrument and method they used
peak RRT area% note
1 0.42 0.31 solvent front
2 0.88 0.44 related substance
3 1.00 98.72 main
4 1.14 0.53 related substanceis sterility tested as part of a normal purity certificate
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Reminder for taper_or_not: dose day is today. Set 8 days ago.
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i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does
lot-log.csv
407 rows · not retained in the public archive
if you only read one line on a certificate, read the lot number. if you read two, read the assay
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update from 2 months ago: started asking every supplier for water content and about half now include it