not evidence on its own
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#coa-reading 2025-04-20
Sunday42 messages8 participantstimes are UTC
Highlights from this day
- fasting_insulin — a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists 20:36
- fasting_insulin — the paperwork can be perfect and the vial can still be light. weigh it 21:51
- area_percent — slightly off topic but gross mass on a jewellery scale plus the water content is enough to catch most underfills retention time shifts between runs are normal.… 22:26
is a supplier certificate worth anything on its own
thats the counterion
[edited]net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial
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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an identical chromatogram on two different lots is the single biggest tell there is, ask me again in a month
purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions, still working it out
test it yourself
i asked BCH for the method and they sent it. that alone put them ahead of most
no lot no certificate
slightly off topic but whats the minimum a certificate has to have before you take it seriously
weigh the vial
if you only read one line on a certificate, read the lot number. if you read two, read the assay
is area percent the same thing as how many mg are in the vial
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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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one decimal versus two is usually just house style, not precision
for the archive the certificate from FGP is the one i use to teach this because it actually has a populated impurity table
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purity is not assay
thats a tell
i have never seen a research certificate with an endotoxin result on it. not once
same chromatogram
net not gross
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sloppy not sinister
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thats a real table
the paperwork can be perfect and the vial can still be light. weigh it
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why do some certificates report to one decimal and some to two
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check the lot
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ask for water content
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the honest summary is that a certificate tells you what the supplier says about a lot they chose to test, n of 1 obviously
genuine question a certificate should name the method, the instrument, the column and the operator. most name none of those
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does anyone keep a folder of certificates to compare over time
follow up tfa or acetate, how do i tell from the paperwork
sterility and endotoxin are separate tests and almost nobody runs either on research material
| 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 |
slightly off topic but gross mass on a jewellery scale plus the water content is enough to catch most underfills
retention time shifts between runs are normal. relative retention time is the number to compare
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 / 10mgmy 2mg vial weighed more than 2mg of powder, is the certificate lying
*Medutest not the other one
the font on this one changes halfway down, am i being paranoid
water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it
coming back after 17 months, has the pinned reading guide changed
looks re-dated
mixed fonts and inconsistent kerning in one document is worth a second look
whats the related substances table actually telling me