#coa-reading 2025-09-10

Wednesday16 messages5 participantstimes are UTC

Highlights from this day

assay_not_purity — i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does 18:50
assay_not_purity — tfa counterion runs higher by mass than acetate. if the certificate does not say, you cannot do the mass balance, i have it written down somewhere 18:55
underfill_uma — a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully 18:57
assay_not_purity — unrelated but a certificate should name the method, the instrument, the column and the operator. most name none of those 19:45
VialBot — Inter-lab diff for lot H-2814: 98.1% vs 99%. Within expected range. 19:47

what does net peptide content mean next to gross mass

not detected means nothing

update on the earlier thing is area percent the same thing as how many mg are in the vial

is sterility tested as part of a normal purity certificate

gross mass on a jewellery scale plus the water content is enough to catch most underfills

mixed fonts and inconsistent kerning in one document is worth a second look, your mileage will differ

genuine question nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself

i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does

test it yourself

📈2😂1

net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial

tfa counterion runs higher by mass than acetate. if the certificate does not say, you cannot do the mass balance, i have it written down somewhere

a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully

😂1📈10🧊6

same chromatogram

transit-times.csv

464 rows · not retained in the public archive

unrelated but a certificate should name the method, the instrument, the column and the operator. most name none of those

✅1📉6

Inter-lab diff for lot H-2814: 98.1% vs 99%. Within expected range.

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does purity by hplc at one wavelength miss things

[edited]