How should peptides be stored, powder vs after mixing?

I want to understand storage before anything else. Does a freeze-dried vial need the same conditions as one that has already been reconstituted?

Storage conditions are not the same for the two states, so it helps to separate them. Lyophilized (freeze-dried) powder is generally more stable and is often kept cold and away from light and moisture, while a reconstituted vial is a liquid and is usually treated as much more perishable and kept refrigerated. Heat, repeated temperature swings, and light are the usual enemies, so minimizing exposure during shipping and handling matters too. Always follow the specific storage notes tied to the exact product rather than a general rule of thumb. This is general information, not medical advice. Do not buy or sell prescription or illegal substances on this forum. Learn more: How to read a peptide COA

Storage gets overlooked a lot.

The mechanism explanation helped, thanks.