Peptide storage basics: sealed vs. mixed vials

Sealed (freeze-dried) vials

Freeze-dried peptides are fairly stable while the vial stays sealed. They are usually kept in the fridge, or the freezer for longer storage, away from light. Many vendors say short periods at room temperature, such as during shipping, are fine. Check the guidance for the product you bought.

Mixed (reconstituted) vials

Once a peptide is mixed with liquid, it is much less stable. Mixed vials are usually kept in the fridge, not the freezer, and used within a set number of days or weeks. That window depends on the compound and the liquid used, so note the vendor's guidance and pick a use-by date when you mix.

What breaks peptides down

• Heat: warm temperatures speed up breakdown
• Light: keep vials in their box or a dark spot
• Moisture: let a cold vial come to room temperature before opening it so condensation does not form inside
• Repeated freezing and thawing: avoid freezing mixed vials

Label everything

Write these on the vial or in your log the moment you mix:

• Mix date
• How much liquid you added
• The use-by date you chose
• A short code or initials if you share a fridge

How The Pep Planner handles it

When you mix a vial with the reconstitution calculator, The Pep Planner saves the mix date, the amount of liquid and the use-by date you set, and keeps mixed vials in their own list. Sealed stock stays in your stockpile with its own count, so you always know which is which.

Common questions

Can I freeze a mixed vial?

Freezing mixed vials is generally avoided because freeze-thaw cycles can break peptides down. Follow the vendor's guidance for the product.

Does bacteriostatic water make a mix last longer?

It contains a small amount of preservative (benzyl alcohol) that limits bacterial growth in a multi-use vial. It does not stop the peptide itself from breaking down over time.