an identical chromatogram on two different lots is the single biggest tell there is
#coa-reading 2026-05-17
Sunday54 messages9 participantstimes are UTC
Highlights from this day
- myrrh_measures — single wavelength detection can miss a co-eluting impurity that does not absorb there 17:03
- seven_five_sweet — slightly off topic but the retention time on this one is different from the last lot, problem 17:52
- fasting_insulin — one decimal versus two is usually just house style, not precision nobody can authenticate a certificate from a scan. you authenticate the material by testing it… 19:16
what does net peptide content mean next to gross mass
i have never seen a research certificate with an endotoxin result on it. not once
update on the earlier thing i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does
does anyone actually check the residual solvents section
slightly off topic but is area percent the same thing as how many mg are in the vial
for the archive water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it
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not evidence on its own
lot-log.csv
492 rows · not retained in the public archive
weigh the vial
test it yourself
is there a standard layout or does every lab do their own
residual solvents matter more than people think for anything that went through a lot of purification steps
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single wavelength detection can miss a co-eluting impurity that does not absorb there
medutest-report-b-0114.pdf
3 pages · 265 KB · not retained in the public archive
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nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
sorry to jump in i keep every certificate in a dated folder and compare them. two suppliers had not changed their template since 2019
update on the earlier thing if you only read one line on a certificate, read the lot number. if you read two, read the assay
a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists
i asked SSA for the method and they sent it. that alone put them ahead of most
the three way match is vial, certificate, invoice. if all three agree you have something
looks re-dated
does purity by hplc at one wavelength miss things
is a supplier certificate worth anything on its own
the related substances table is the interesting part. a row of "not detected" means they did not look hard
nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
slightly off topic but the retention time on this one is different from the last lot, problem
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*Janoshik not the other one
why would a vial be 98.6 pure and still assay under label
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not
update from 12 months ago: started asking every supplier for water content and about half now include it
is sterility tested as part of a normal purity certificate
should a certificate say which instrument and method they used
net not gross
net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial
why do some certificates report to one decimal and some to two
two certificates from the same supplier have an identical chromatogram, is that normal
coming back to this the paperwork can be perfect and the vial can still be light. weigh it
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is water content normally on a certificate or do you have to ask
retention time shifts between runs are normal. relative retention time is the number to compare, your mileage will differ
thats the counterion
purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions
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one decimal versus two is usually just house style, not precision
nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
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genuine question gross mass on a jewellery scale plus the water content is enough to catch most underfills
no lot no certificate
thats a tell
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tfa or acetate, how do i tell from the paperwork
no lot number on this certificate, does that make it worthless
sloppy not sinister
not detected means nothing
coming back after 4 months, has the pinned reading guide changed
thats a real table
a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully
same chromatogram
how do you verify a certificate is actually from the lab it says
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good certificate actually
while im here a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists