net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial
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#coa-reading 2025-12-19
Friday27 messages6 participantstimes are UTC
Highlights from this day
- coelution_cai — net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial 11:39
- a1c_lag — one decimal versus two is usually just house style, not precision 13:09
- HPLC_Hank — 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, i could be wrong 15:06
purity is not assay
i have never seen a research certificate with an endotoxin result on it. not once
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gross mass on a jewellery scale plus the water content is enough to catch most underfills
whats the minimum a certificate has to have before you take it seriously
residual solvents matter more than people think for anything that went through a lot of purification steps
*that should say weekly
purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions
while im here whats the related substances table actually telling me
my 15mg vial weighed more than 20mg of powder, is the certificate lying
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not, n of 1 obviously
one decimal versus two is usually just house style, not precision
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the retention time on this one is different from the last lot, problem
for the archive no lot number on this certificate, does that make it worthless
ask for water content
a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully
retention time shifts between runs are normal. relative retention time is the number to compare
the related substances table is the interesting part. a row of "not detected" means they did not look hard
same chromatogram
net not gross
mixed fonts and inconsistent kerning in one document is worth a second look
the honest summary is that a certificate tells you what the supplier says about a lot they chose to test
does anyone keep a folder of certificates to compare over time
the paperwork can be perfect and the vial can still be light. weigh it, for what its worth
*Medutest not the other one
no lot number, no certificate. a document you cannot tie to the vial in your hand is decoration
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, i could be wrong
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