#coa-reading 2026-02-18

Wednesday15 messages4 participantstimes are UTC

Highlights from this day

mhra_unlicensed — if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not, we shall see 13:50
mhra_unlicensed — a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists, happy to be corrected 14:05
fasting_insulin — water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it 14:08
peak_split — an identical chromatogram on two different lots is the single biggest tell there is 16:19
peak_split — sterility and endotoxin are separate tests and almost nobody runs either on research material 16:25

if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not, we shall see

a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists, happy to be corrected

fasting_insulin 14:08

water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it

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mhra_unlicensed 14:57

what does net peptide content mean next to gross mass

ask for water content

mhra_unlicensed 15:13

why do some certificates report to one decimal and some to two

mhra_unlicensed 15:28

two certificates from the same supplier have an identical chromatogram, is that normal

[edited]

mhra_unlicensed 16:09

the related substances table is the interesting part. a row of "not detected" means they did not look hard

no lot number, no certificate. a document you cannot tie to the vial in your hand is decoration

lisbon_lot 16:12

good certificate actually

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

mhra_unlicensed if the certificate date precedes the lot date, ask. sometimes it is sloppiness and…

lisbon_lot 16:18

i keep every certificate in a dated folder and compare them. two suppliers had not changed their template since 2019

peak_splitlab16:19

an identical chromatogram on two different lots is the single biggest tell there is

fridge-thermometer.png

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peak_splitlab16:25

sterility and endotoxin are separate tests and almost nobody runs either on research material

peak   RRT    area%    note
  1   0.42     0.31    solvent front
  2   0.88     0.44    related substance
  3   1.00    98.72    main
  4   1.14     0.53    related substance

purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions