thats a real table
#coa-reading 2024-10-06
Sunday30 messages6 participantstimes are UTC
Highlights from this day
- lot_number_lou — right so i asked Homopeptide for the method and they sent it. that alone put them ahead of most 18:19
- bea_reconstitutes — slightly off topic but water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it 19:37
- HPLC_Hank — update on the earlier thing i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does 19:52
- bea_reconstitutes — retention time shifts between runs are normal. relative retention time is the number to compare, i have it written down somewhere 20:09
- reship_rita — no lot number on this certificate, does that make it worthless an identical chromatogram on two different lots is the single biggest tell there is 20:55
right so i asked Homopeptide for the method and they sent it. that alone put them ahead of most
tfa or acetate, how do i tell from the paperwork
the related substances table is the interesting part. a row of "not detected" means they did not look hard
the retention time on this one is different from the last lot, problem
if you only read one line on a certificate, read the lot number. if you read two, read the assay
why do some certificates report to one decimal and some to two
tfa counterion runs higher by mass than acetate. if the certificate does not say, you cannot do the mass balance
purity is not assay
my 5mg vial weighed more than 10mg of powder, is the certificate lying
slightly off topic but water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it
looks re-dated
check the lot
update on the earlier thing i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does
i keep every certificate in a dated folder and compare them. two suppliers had not changed their template since 2019
retention time shifts between runs are normal. relative retention time is the number to compare, i have it written down somewhere
no lot number, no certificate. a document you cannot tie to the vial in your hand is decoration
why would a vial be 96.8 pure and still assay under label
ask for water content
no lot number on this certificate, does that make it worthless
an identical chromatogram on two different lots is the single biggest tell there is
is water content normally on a certificate or do you have to ask
no lot no certificate
the honest summary is that a certificate tells you what the supplier says about a lot they chose to test
two certificates from the same supplier have an identical chromatogram, is that normal
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
net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial
net not gross
follow up mixed fonts and inconsistent kerning in one document is worth a second look, your mileage will differ