purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions
#coa-reading 2026-01-11
Sunday13 messages3 participantstimes are UTC
Highlights from this day
- otto_swirls — purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions 19:57
- otto_swirls — water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it 20:17
- area_percent — 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 20:32
- lisbon_lot — the honest summary is that a certificate tells you what the supplier says about a lot they chose to test, anyway 21:20
water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it
ask for water content
looks re-dated
not evidence on its own
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 / 10mgthe related substances table is the interesting part. a row of "not detected" means they did not look hard
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
the three way match is vial, certificate, invoice. if all three agree you have something
purity is not assay
the honest summary is that a certificate tells you what the supplier says about a lot they chose to test, anyway
weigh the vial
nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
what does net peptide content mean next to gross mass