the related substances table is the interesting part. a row of "not detected" means they did not look hard
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#coa-reading 2026-04-30
Thursday13 messages3 participantstimes are UTC
Highlights from this day
- salt_bridge — the related substances table is the interesting part. a row of "not detected" means they did not look hard 18:02
- two_three_lifts — tfa or acetate, how do i tell from the paperwork gross mass on a jewellery scale plus the water content is enough to catch most underfills 18:35
- salt_bridge — whats the related substances table actually telling me an identical chromatogram on two different lots is the single biggest tell there is 19:05
- salt_bridge — tfa counterion runs higher by mass than acetate. if the certificate does not say, you cannot do the mass balance, take that with a pinch of salt 19:15
thats a real table
the paperwork can be perfect and the vial can still be light. weigh it
tfa or acetate, how do i tell from the paperwork
gross mass on a jewellery scale plus the water content is enough to catch most underfills
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good certificate actually
does anyone keep a folder of certificates to compare over time
update from 18 months ago: started asking every supplier for water content and about half now include it
same chromatogram
whats the related substances table actually telling me
an identical chromatogram on two different lots is the single biggest tell there is
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the certificate from Homopeptide is the one i use to teach this because it actually has a populated impurity table
tfa counterion runs higher by mass than acetate. if the certificate does not say, you cannot do the mass balance, take that with a pinch of salt
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should a certificate say which instrument and method they used
if you only read one line on a certificate, read the lot number. if you read two, read the assay
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