no lot number, no certificate. a document you cannot tie to the vial in your hand is decoration
#coa-reading 2026-03-06
Friday34 messages6 participantstimes are UTC
Highlights from this day
- nine_nine_one — i asked ERP for the method and they sent it. that alone put them ahead of most 01:10
- nine_nine_one — water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it, happy to be corrected 01:25
- void_volume — why would a vial be 99 pure and still assay under label 02:02
- forty_five_kg — sterility and endotoxin are separate tests and almost nobody runs either on research material 06:03
sorry to jump in is there a standard layout or does every lab do their own
does purity by hplc at one wavelength miss things
Reminder set. I will post here in 3 days.
i asked ERP for the method and they sent it. that alone put them ahead of most
whats the minimum a certificate has to have before you take it seriously
water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it, happy to be corrected
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residual solvents matter more than people think for anything that went through a lot of purification steps
not evidence on its own
mixed fonts and inconsistent kerning in one document is worth a second look
retention time shifts between runs are normal. relative retention time is the number to compare
the font on this one changes halfway down, am i being paranoid
no lot number on this certificate, does that make it worthless
i have never seen a research certificate with an endotoxin result on it. not once
why would a vial be 99 pure and still assay under label
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test it yourself
no lot no certificate
should a certificate say which instrument and method they used
follow up single wavelength detection can miss a co-eluting impurity that does not absorb there
*PeptideMeter not the other one
net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial
ok so i have never seen a research certificate with an endotoxin result on it. not once, thats one data point
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tfa counterion runs higher by mass than acetate. if the certificate does not say, you cannot do the mass balance
my 15mg vial weighed more than 5mg of powder, is the certificate lying
same chromatogram
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whats the related substances table actually telling me
the certificate from QSC 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
sterility and endotoxin are separate tests and almost nobody runs either on research material
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purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions
looks re-dated
lot bought purity assay/label
A-2418 2025-03 99.1% 9.6 / 10mg
A-2601 2025-08 98.7% 9.8 / 10mg
B-0114 2026-01 99.3% 9.4 / 10mg
B-0329 2026-04 98.9% 9.9 / 10mgwhile im here i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does
coming back after 23 months, has the pinned reading guide changed
purity is not assay
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thats a real table
thats a tell