check the lot
#coa-reading 2025-02-22
Saturday31 messages6 participantstimes are UTC
Highlights from this day
good certificate actually
purity is not assay
Recon calculator: 15mg in 0.5ml = 2mg/ml.
update from 14 months ago: started asking every supplier for water content and about half now include it
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is sterility tested as part of a normal purity certificate
same chromatogram
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i have never seen a research certificate with an endotoxin result on it. not once, someone check my working
no lot no certificate
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if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not
should a certificate say which instrument and method they used
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ask for water content
gross mass on a jewellery scale plus the water content is enough to catch most underfills
peptidemeter-summary-d-0718.pdf
2 pages · 473 KB · not retained in the public archive
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sloppy not sinister
a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists
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right so an identical chromatogram on two different lots is the single biggest tell there is, thats one data point
is water content normally on a certificate or do you have to ask
if you only read one line on a certificate, read the lot number. if you read two, read the assay
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not detected means nothing
slightly off topic but why would a vial be 99 pure and still assay under label
Reminder for ten_percent_off: dose day is today. Set 3 days ago.
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is endotoxin ever tested on research material
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 / 10mgtest it yourself
Recon calculator: 15mg in 3ml = 4mg/ml.
thats a real table
| Line | Claims | Does not claim |
|---|---|---|
| Purity (area %) | fraction of detected material that is the target | how many mg are in the vial |
| Assay / content | mg of target per vial | that it is sterile |
| Water content | mass fraction that is water | anything about purity |
| Counterion | salt form and its mass share | net peptide unless stated |
| Related substances | what else was seen | what was not looked for |
sorry to jump in my 10mg vial weighed more than 30mg of powder, is the certificate lying
residual solvents matter more than people think for anything that went through a lot of purification steps
[edited]whats the minimum a certificate has to have before you take it seriously
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 related substances table is the interesting part. a row of "not detected" means they did not look hard
looks re-dated