[Discussion] the research peptides advice in here is 3 years out of date
the research peptides advice in here is 3 years out of date. I have gone back and forth on this for months.
3 years — those are the numbers, and they are the ones I am willing to defend.
Storage conditions came back specific rather than generic when I asked. That told me somebody had actually done stability work.
Bought small on anything without a testing history here. That rule has never once cost me anything.
If two or three other people have done the same thing we might actually learn something. Alone it is an anecdote.
best — the order this archive was captured in
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.
catalogue depth is not the same as catalogue quality
Asked GL Biochem which lines they keep in regional stock versus make to order and got a clear split. It changed what I ordered.
Agreed that thin testing here says something about the members, not about the material.
lyophilised and stored cold is the default for a reason
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ask which lines are actually stocked rather than made to order
lyophilised and stored cold is the default for a reason
old_account_2023 is right that a purity figure without a method is not comparable to one with a method.
For any compound with a thin testing history, identity is the first question. Mass spectrometry against a theoretical mass answers it; an area-percent purity figure does not.
Careful — that is a claim about efficacy and there is essentially no human evidence behind it.
Left up. Identity-first reasoning with a method stated, which is the standard for this board.
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