i asked BCH for the method and they sent it. that alone put them ahead of most
#coa-reading 2026-06-11
Thursday59 messages13 participantstimes are UTC
Highlights from this day
- ghent_gradient — purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions 21:26
- endotoxin_ed — the related substances table is the interesting part. a row of "not detected" means they did not look hard 23:00
- two_three_lifts — the honest summary is that a certificate tells you what the supplier says about a lot they chose to test 23:49
test it yourself
net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not
[edited]unrelated but coming back after 13 months, has the pinned reading guide changed
net not gross
water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it
purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions
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the font on this one changes halfway down, am i being paranoid
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update from 10 months ago: started asking every supplier for water content and about half now include it
the paperwork can be perfect and the vial can still be light. weigh it, take that with a pinch of salt
thats a real table
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whats the minimum a certificate has to have before you take it seriously
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genuine question the honest summary is that a certificate tells you what the supplier says about a lot they chose to test
while im here is a supplier certificate worth anything on its own
purity is not assay
the certificate from JEEP is the one i use to teach this because it actually has a populated impurity table
i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does
mixed fonts and inconsistent kerning in one document is worth a second look, someone check my working
nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
why would a vial be 99.4 pure and still assay under label
genuine question is sterility tested as part of a normal purity certificate
fridge-temps.csv
150 rows · not retained in the public archive
ask for water content
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how do you verify a certificate is actually from the lab it says
i keep every certificate in a dated folder and compare them. two suppliers had not changed their template since 2019
a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists
one decimal versus two is usually just house style, not precision
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nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
thats the counterion
certificate is dated before the lot date, is that just sloppiness
sterility and endotoxin are separate tests and almost nobody runs either on research material
a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully
the certificate from FGP is the one i use to teach this because it actually has a populated impurity table
impersonator_ipupdate from 10 months ago: started asking every supplier for water content and about…
is endotoxin ever tested on research material
residual solvents matter more than people think for anything that went through a lot of purification steps
is area percent the same thing as how many mg are in the vial
not detected means nothing
retention time shifts between runs are normal. relative retention time is the number to compare
[edited]Recon calculator: 10mg in 1.5ml = 8mg/ml.
should a certificate say which instrument and method they used
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
check the lot
right so two certificates from the same supplier have an identical chromatogram, is that normal
tfa counterion runs higher by mass than acetate. if the certificate does not say, you cannot do the mass balance
the certificate from KP is the one i use to teach this because it actually has a populated impurity table
looks re-dated
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good certificate actually
the three way match is vial, certificate, invoice. if all three agree you have something
no lot number, no certificate. a document you cannot tie to the vial in your hand is decoration
a certificate should name the method, the instrument, the column and the operator. most name none of those
the related substances table is the interesting part. a row of "not detected" means they did not look hard
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weigh the vial
gross mass on a jewellery scale plus the water content is enough to catch most underfills, i could be wrong
update from 16 months ago: started asking every supplier for water content and about half now include it
not evidence on its own
sloppy not sinister
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is there a standard layout or does every lab do their own
an identical chromatogram on two different lots is the single biggest tell there is
if you only read one line on a certificate, read the lot number. if you read two, read the assay
i have never seen a research certificate with an endotoxin result on it. not once
the honest summary is that a certificate tells you what the supplier says about a lot they chose to test
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sloppy not sinister