net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial
#coa-reading 2026-03-25
Wednesday34 messages9 participantstimes are UTC
Highlights from this day
- typosquat_tay — my 40mg vial weighed more than 20mg of powder, is the certificate lying 20:19
- typosquat_tay — no lot number, no certificate. a document you cannot tie to the vial in your hand is decoration, thats just me 20:32
- nettle_notes — update from 23 months ago: started asking every supplier for water content and about half now include it 21:31
- nettle_notes — the honest summary is that a certificate tells you what the supplier says about a lot they chose to test 21:46
the three way match is vial, certificate, invoice. if all three agree you have something
*Janoshik not the other one
thats a tell
whats the minimum a certificate has to have before you take it seriously
slightly off topic but purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions
❤️10⚠️1
i have never seen a research certificate with an endotoxin result on it. not once
💀5🧊10
mixed fonts and inconsistent kerning in one document is worth a second look
a certificate should name the method, the instrument, the column and the operator. most name none of those
my 40mg vial weighed more than 20mg of powder, is the certificate lying
📉1👍17
the retention time on this one is different from the last lot, problem
purity is not assay
no lot number, no certificate. a document you cannot tie to the vial in your hand is decoration, thats just me
❤️3💀17⚠️5
is area percent the same thing as how many mg are in the vial
🧊9
no lot number on this certificate, does that make it worthless
net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial
if you only read one line on a certificate, read the lot number. if you read two, read the assay, i could be wrong
retention time shifts between runs are normal. relative retention time is the number to compare
thats a real table
does anyone actually check the residual solvents section
single wavelength detection can miss a co-eluting impurity that does not absorb there
sterility and endotoxin are separate tests and almost nobody runs either on research material
what does net peptide content mean next to gross mass
sorry to jump in tfa counterion runs higher by mass than acetate. if the certificate does not say, you cannot do the mass balance
📈2🧪1
nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
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
residual_solventsterility and endotoxin are separate tests and almost nobody runs either on research…
one decimal versus two is usually just house style, not precision
i asked GL Biochem for the method and they sent it. that alone put them ahead of most
👍10
update from 23 months ago: started asking every supplier for water content and about half now include it
❤️17📉2
ask for water content
Reminder for fridge_thermo: dose day is today. Set 3 days ago.
the honest summary is that a certificate tells you what the supplier says about a lot they chose to test
👀1🎉14🧊6
a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not
should a certificate say which instrument and method they used
quick one does purity by hplc at one wavelength miss things
genuine question why would a vial be 96.8 pure and still assay under label
medutest-report-sg-1177.pdf
3 pages · 560 KB · not retained in the public archive