certificate is dated before the lot date, is that just sloppiness
#coa-reading 2025-09-05
Friday30 messages6 participantstimes are UTC
Highlights from this day
- lot_number_lou — retention time shifts between runs are normal. relative retention time is the number to compare 21:11
- void_volume — is water content normally on a certificate or do you have to ask 22:14
- area_percent — residual solvents matter more than people think for anything that went through a lot of purification steps 22:24
- area_percent — one decimal versus two is usually just house style, not precision the paperwork can be perfect and the vial can still be light. weigh it 22:40
- cold_chain_cmdr — water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it a supplier certificate on its own is a starting point,… 22:47
coming back to this a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists
the honest summary is that a certificate tells you what the supplier says about a lot they chose to test
why would a vial be 98.6 pure and still assay under label
retention time shifts between runs are normal. relative retention time is the number to compare
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 substancelooks re-dated
whats the related substances table actually telling me
tfa or acetate, how do i tell from the paperwork
no lot number on this certificate, does that make it worthless
why do some certificates report to one decimal and some to two
not evidence on its own
the retention time on this one is different from the last lot, problem
should a certificate say which instrument and method they used
purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions
for the archive whats the minimum a certificate has to have before you take it seriously
single wavelength detection can miss a co-eluting impurity that does not absorb there
mixed fonts and inconsistent kerning in one document is worth a second look
is water content normally on a certificate or do you have to ask
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good certificate actually
residual solvents matter more than people think for anything that went through a lot of purification steps
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 substanceif the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not
is there a standard layout or does every lab do their own
is sterility tested as part of a normal purity certificate
one decimal versus two is usually just house style, not precision
the paperwork can be perfect and the vial can still be light. weigh it
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 substancehow do you verify a certificate is actually from the lab it says
sorry to jump in coming back after 19 months, has the pinned reading guide changed
ask for water content
water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it
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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is a supplier certificate worth anything on its own
update from 22 months ago: started asking every supplier for water content and about half now include it