#coa-reading 2025-05-08

Thursday28 messages6 participantstimes are UTC

Highlights from this day

HPLC_Hank — should a certificate say which instrument and method they used 21:52
VialBot — Reminder for taper_or_not: dose day is today. Set 8 days ago. 22:18
taper_or_not — if you only read one line on a certificate, read the lot number. if you read two, read the assay 22:23

whats the minimum a certificate has to have before you take it seriously

i have never seen a research certificate with an endotoxin result on it. not once

one decimal versus two is usually just house style, not precision

a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists
residual solvents matter more than people think for anything that went through a lot of purification steps

chlorhexmod20:12

looks re-dated

the certificate from Homopeptide 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

taper_or_not 20:25

ask for water content

does anyone actually check the residual solvents section

fridge-thermometer.png

800 × 800 · 516 KB · not retained in the public archive

salt_bridgelab20:39

residual solvents matter more than people think for anything that went through a lot of purification steps

chlorhexmod20:50

no lot number on this certificate, does that make it worthless

sloppy not sinister

🔥1⚠️12

chlorhexmod21:02

update on the earlier thing net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial

⚠️9

whats the related substances table actually telling me

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

chlorhex sloppy not sinister

lean_mass_lex 21:05

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

lean_mass_lex 21:19

not evidence on its own

✅3

HPLC_Hanklab21:21

same chromatogram

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

lean_mass_lex 21:25

is endotoxin ever tested on research material

HPLC_Hank purity is what fraction of the contents is the target. assay is how many mg are…

lean_mass_lex 21:38

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

weights-monthly.csv

902 rows · not retained in the public archive

a certificate should name the method, the instrument, the column and the operator. most name none of those

HPLC_Hanklab21:52

should a certificate say which instrument and method they used

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

lean_mass_lex 22:17

is sterility tested as part of a normal purity certificate

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VialBotbot22:18

Reminder for taper_or_not: dose day is today. Set 8 days ago.

📈15🧪5

salt_bridgelab22:21

i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does

lot-log.csv

407 rows · not retained in the public archive

taper_or_not 22:23

if you only read one line on a certificate, read the lot number. if you read two, read the assay

🔥11

update from 2 months ago: started asking every supplier for water content and about half now include it