[Discussion] the thymosin advice in here is 3 years out of date
Posting this as a discussion rather than a claim: the thymosin advice in here is 3 years out of date. Pulling the figures out of the title: 3 years. All of it is written down as it happened rather than reconstructed. The three questions to ask before ordering anything from the long tail of a catalogue. What exactly…
Why purity and net content diverge, and why that is usually honest.
Purity by area percent is a relative measure of what the detector saw. Net peptide content subtracts counterion, water and residual solvent from the powder mass. For some compounds in this catalogue the gap between the two is large.
A vial can therefore be 99% pure and contain considerably less peptide by mass than the label weight suggests, with nothing wrong anywhere. The problem is not the chemistry; it is that people compare a purity figure from one supplier with a net content figure from another and conclude something about both. Ask which number you are being shown, every time.
Identity confirmed, or purity only?
the less-tested the compound, the more the identity test matters
Small fix — that is net peptide content, not purity. Both are on the certificate and they differ substantially here.
Net peptide content accounts for counterion, water and residual solvent. On some of these compounds the gap between purity and net content is substantial and entirely honest.