net not gross
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#coa-reading 2025-08-21
Thursday19 messages5 participantstimes are UTC
Highlights from this day
- fasting_insulin — the certificate from GGPeps is the one i use to teach this because it actually has a populated impurity table 16:52
- lot_number_lou — 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, your mileage will differ 18:03
- split_shipment — quick one water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it 18:17
follow up nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
no lot number, no certificate. a document you cannot tie to the vial in your hand is decoration
the certificate from GGPeps is the one i use to teach this because it actually has a populated impurity table
residual solvents matter more than people think for anything that went through a lot of purification steps
i keep every certificate in a dated folder and compare them. two suppliers had not changed their template since 2019, we shall see
[edited]purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions, ask me again in a month
retention time shifts between runs are normal. relative retention time is the number to compare
i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does
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, your mileage will differ
a certificate should name the method, the instrument, the column and the operator. most name none of those
same chromatogram
quick one water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it
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one decimal versus two is usually just house style, not precision
if you only read one line on a certificate, read the lot number. if you read two, read the assay
an identical chromatogram on two different lots is the single biggest tell there is
thats a tell
purity is not assay
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is endotoxin ever tested on research material