handling — 9 things I got wrong before I got it right
handling — 9 things I got wrong before I got it right — a position I have arrived at slowly and would like tested.
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.
Naming in this space is inconsistent. Several widely used names map to more than one molecule, so a catalogue number and a sequence beat a common name every time.
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.
If somebody has the same thing measured a different way, post it next to mine and we will see whether they agree.
best — the order this archive was captured in
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.
Asked JEEP which lines they keep in regional stock versus make to order and got a clear split. It changed what I ordered.
Stocked lines and made-to-order lines have different lead times and different storage histories. Both are ordinary; the difference is worth confirming before you commit.
ask which lines are actually stocked rather than made to order
Storage guidance that names a temperature, a state and a duration reflects actual stability work. Generic guidance usually reflects a template.
Small fix — that is net peptide content, not purity. Both are on the certificate and they differ substantially here.
lyophilised and stored cold is the default for a reason
Research-use-only material is not approved for human use. In this catalogue that covers essentially everything, which is why the board discusses material and analytics rather than outcomes.
Net peptide content on the certificate was well below the purity figure and both were honest. Chemistry, not deception.
the same name covers several different molecules in this space
- 1Storage guidance that names a temperature, a state and a duration reflects…6 comments in this branch · started by u/deleted_my_history