does anyone keep a folder of certificates to compare over time
#coa-reading 2026-03-31
Tuesday13 messages4 participantstimes are UTC
Highlights from this day
- travel_cooler — no lot number on this certificate, does that make it worthless 15:30
- VialBot — Assay note: MKM lot B-0114 reported at 97.4% of label content. 16:24
- travel_cooler — gross mass on a jewellery scale plus the water content is enough to catch most underfills water content is why an honest 10mg vial assays at 9.1. karl fischer… 16:33
- travel_cooler — genuine question one decimal versus two is usually just house style, not precision sterility and endotoxin are separate tests and almost nobody runs either on… 17:07
- pinch_not_stretch — slightly off topic but an identical chromatogram on two different lots is the single biggest tell there is, from memory 17:35
update from 19 months ago: started asking every supplier for water content and about half now include it, still working it out
no lot number on this certificate, does that make it worthless
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quick one net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial
purity is not assay
Assay note: MKM lot B-0114 reported at 97.4% of label content.
retention time shifts between runs are normal. relative retention time is the number to compare
gross mass on a jewellery scale plus the water content is enough to catch most underfills
water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it
the retention time on this one is different from the last lot, problem
genuine question one decimal versus two is usually just house style, not precision
sterility and endotoxin are separate tests and almost nobody runs either on research material
slightly off topic but an identical chromatogram on two different lots is the single biggest tell there is, from memory
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sorry to jump in why would a vial be 98.6 pure and still assay under label
i keep every certificate in a dated folder and compare them. two suppliers had not changed their template since 2019, not advice obviously