residual solvents matter more than people think for anything that went through a lot of purification steps, thats one data point
#coa-reading 2025-08-30
Saturday39 messages9 participantstimes are UTC
Highlights from this day
- VialBot — Reminder for thank_you_year_on: dose day is today. Set 4 days ago. 14:40
- peak_split — two certificates from the same supplier have an identical chromatogram, is that normal 15:21
- vialkeeper — my 30mg vial weighed more than 10mg of powder, is the certificate lying 16:02
- kev_measures — the related substances table is the interesting part. a row of "not detected" means they did not look hard 16:41
- lisbon_lot — an identical chromatogram on two different lots is the single biggest tell there is 18:02
thats a real table
purity is not assay
the font on this one changes halfway down, am i being paranoid
slightly off topic but does anyone keep a folder of certificates to compare over time
water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it
ok so is a supplier certificate worth anything on its own
gross mass on a jewellery scale plus the water content is enough to catch most underfills
same chromatogram
does anyone actually check the residual solvents section
a certificate should name the method, the instrument, the column and the operator. most name none of those
sterility and endotoxin are separate tests and almost nobody runs either on research material
is area percent the same thing as how many mg are in the vial
Reminder for thank_you_year_on: dose day is today. Set 4 days ago.
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whats the related substances table actually telling me
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
two certificates from the same supplier have an identical chromatogram, is that normal
| 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 |
follow up the three way match is vial, certificate, invoice. if all three agree you have something
residual solvents matter more than people think for anything that went through a lot of purification steps
thats a tell
is sterility tested as part of a normal purity certificate
no lot no certificate
nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
the paperwork can be perfect and the vial can still be light. weigh it
whats the minimum a certificate has to have before you take it seriously
update on the earlier thing is endotoxin ever tested on research material
my 30mg vial weighed more than 10mg of powder, is the certificate lying
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the related substances table is the interesting part. a row of "not detected" means they did not look hard
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Inter-lab diff for lot A-2418: 99.4% vs 98.1%. Within expected range.
net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial
not detected means nothing
not evidence on its own
an identical chromatogram on two different lots is the single biggest tell there is
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ask for water content
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not
i asked BCH for the method and they sent it. that alone put them ahead of most
the retention time on this one is different from the last lot, problem
coming back after 20 months, has the pinned reading guide changed
purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions, someone check my working