two certificates from the same supplier have an identical chromatogram, is that normal
#coa-reading 2026-04-18
Saturday24 messages6 participantstimes are UTC
Highlights from this day
- lisbon_lot — gross mass on a jewellery scale plus the water content is enough to catch most underfills 15:55
- logrotate — the certificate from JEEP is the one i use to teach this because it actually has a populated impurity table 17:43
- relabel_watch — is there a standard layout or does every lab do their own 17:51
the honest summary is that a certificate tells you what the supplier says about a lot they chose to test
[edited]sterility and endotoxin are separate tests and almost nobody runs either on research material
the retention time on this one is different from the last lot, problem
the honest summary is that a certificate tells you what the supplier says about a lot they chose to test
weigh the vial
a certificate should name the method, the instrument, the column and the operator. most name none of those, ill dig out the number
not detected means nothing
[edited]gross mass on a jewellery scale plus the water content is enough to catch most underfills
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update on the earlier thing 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
tfa or acetate, how do i tell from the paperwork
Testing queue: 9 submissions open, 22 awaiting dispatch.
net not gross
right so one decimal versus two is usually just house style, not precision
update from 17 months ago: started asking every supplier for water content and about half now include it
does purity by hplc at one wavelength miss things
the certificate from JEEP is the one i use to teach this because it actually has a populated impurity table
the three way match is vial, certificate, invoice. if all three agree you have something
whats the minimum a certificate has to have before you take it seriously
is there a standard layout or does every lab do their own
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the related substances table is the interesting part. a row of "not detected" means they did not look hard
i have never seen a research certificate with an endotoxin result on it. not once, i could be wrong
no lot number, no certificate. a document you cannot tie to the vial in your hand is decoration
thats the counterion
i keep every certificate in a dated folder and compare them. two suppliers had not changed their template since 2019