looks re-dated
#coa-reading 2025-01-05
Sunday21 messages5 participantstimes are UTC
Highlights from this day
- abdo_two_inch — tfa counterion runs higher by mass than acetate. if the certificate does not say, you cannot do the mass balance 15:01
- meal_prep_mick — residual solvents matter more than people think for anything that went through a lot of purification steps, happy to be corrected 15:34
- HPLC_Hank — if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not 15:37
- lot_number_lou — sorry to jump in the certificate from WWB is the one i use to teach this because it actually has a populated impurity table 16:38
- reship_rita — purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions, still working it out 17:50
nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself, i have it written down somewhere
tfa counterion runs higher by mass than acetate. if the certificate does not say, you cannot do the mass balance
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unrelated but a certificate should name the method, the instrument, the column and the operator. most name none of those
tfa or acetate, how do i tell from the paperwork
residual solvents matter more than people think for anything that went through a lot of purification steps, happy to be corrected
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if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not
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if you only read one line on a certificate, read the lot number. if you read two, read the assay
right so mixed fonts and inconsistent kerning in one document is worth a second look
my 40mg vial weighed more than 30mg of powder, is the certificate lying
retention time shifts between runs are normal. relative retention time is the number to compare
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net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial
genuine question a vial can be 99.4% pure and hold 8.1mg of a 10mg label. both numbers are true and only one of them is the one you care about
sorry to jump in the certificate from WWB is the one i use to teach this because it actually has a populated impurity table
the related substances table is the interesting part. a row of "not detected" means they did not look hard, n of 1 obviously
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gross mass on a jewellery scale plus the water content is enough to catch most underfills
purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions, still working it out
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is area percent the same thing as how many mg are in the vial
a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists
single wavelength detection can miss a co-eluting impurity that does not absorb there