genuine question single wavelength detection can miss a co-eluting impurity that does not absorb there
#coa-reading 2024-09-20
Friday29 messages7 participantstimes are UTC
Highlights from this day
- truncation_tru — tfa or acetate, how do i tell from the paperwork 19:09
- triple_ag_tom — the certificate from TFC is the one i use to teach this because it actually has a populated impurity table 20:00
- snac_and_water — an identical chromatogram on two different lots is the single biggest tell there is 20:30
- snac_and_water — a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully 20:35
18:44truncation_tru joined
check the lot
should a certificate say which instrument and method they used
tfa or acetate, how do i tell from the paperwork
peak RRT area% note
1 0.42 0.31 solvent front
2 0.88 0.44 related substance
3 1.00 98.72 main
4 1.14 0.53 related substancemixed fonts and inconsistent kerning in one document is worth a second look, n of 1 obviously
no lot number, no certificate. a document you cannot tie to the vial in your hand is decoration
tfa counterion runs higher by mass than acetate. if the certificate does not say, you cannot do the mass balance
Digest for the week of 2024-07-18 has been published.
Testing queue: 7 submissions open, 108 awaiting dispatch.
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while im here is endotoxin ever tested on research material
is sterility tested as part of a normal purity certificate
same chromatogram
net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial
the certificate from TFC is the one i use to teach this because it actually has a populated impurity table
update on the earlier thing i have never seen a research certificate with an endotoxin result on it. not once
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not, not advice obviously
coming back to this the three way match is vial, certificate, invoice. if all three agree you have something
water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it
the related substances table is the interesting part. a row of "not detected" means they did not look hard
two certificates from the same supplier have an identical chromatogram, is that normal
what does net peptide content mean next to gross mass
looks re-dated
no lot no certificate
i asked SSA for the method and they sent it. that alone put them ahead of most, for what its worth
thats a real table
*that should say weekly
update from 4 months ago: started asking every supplier for water content and about half now include it
an identical chromatogram on two different lots is the single biggest tell there is
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a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully
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