should a certificate say which instrument and method they used
#coa-reading 2025-11-01
Saturday23 messages6 participantstimes are UTC
Highlights from this day
- back_from_away — i asked QYB for the method and they sent it. that alone put them ahead of most 16:55
- gradient_greg — update from 11 months ago: started asking every supplier for water content and about half now include it 17:01
- back_from_away — why would a vial be 99 pure and still assay under label 18:54
- assay_not_purity — i have never seen a research certificate with an endotoxin result on it. not once 19:14
i asked QYB for the method and they sent it. that alone put them ahead of most
update from 11 months ago: started asking every supplier for water content and about half now include it
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water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it
for the archive nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
my 30mg vial weighed more than 20mg of powder, is the certificate lying
whats the minimum a certificate has to have before you take it seriously
a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully, ill dig out the number
thats a tell
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follow up does purity by hplc at one wavelength miss things
how do you verify a certificate is actually from the lab it says
the retention time on this one is different from the last lot, problem
why do some certificates report to one decimal and some to two
if you only read one line on a certificate, read the lot number. if you read two, read the assay
purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions
why would a vial be 99 pure and still assay under label
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i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not, ask me again in a month
sterility and endotoxin are separate tests and almost nobody runs either on research material
i have never seen a research certificate with an endotoxin result on it. not once
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single wavelength detection can miss a co-eluting impurity that does not absorb there
residual solvents matter more than people think for anything that went through a lot of purification steps
what does net peptide content mean next to gross mass
mixed fonts and inconsistent kerning in one document is worth a second look