what does net peptide content mean next to gross mass, no rush
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Thread · #coa-reading · 2026-05-20
acetate and tfa carry different mass fractions, so counterion
Spun off from a message in #coa-reading on 2026-05-20. 13 messages, 3 participants.
The message this came from
- mira_pins — acetate and tfa carry different mass fractions, so counterion unstated means the net peptide is unstated a certificate that will not tie to a physical vial is a picture of a document 19:40
good cert actually
on net versus gross again how much does the counterion being unstated actually matter, or have i misread it
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net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial, lot specific not batch
sorry late, good certs are checkable
about the date on these is a mass spec trace on the cert normal or is that a good sign, been going round in circles on it
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water content missing means your mass balance has a hole in it, not that the vial is wrong, small sample obviously
net peptide content is what you are buying and gross mass is what you are weighing. the gap is water and counterion, saved as a pdf
for anyone new to these tfa or acetate, how do i tell from the paperwork
pdf in a folder
the retention time on this one is different from the last lot, problem, i have looked and cannot find it
small thing on the impurity table method, wavelength, column, gradient. a purity number without those is a number someone typed, net peptide not gross
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not