Lyophilised (freeze-dried)

Lyophilisation, or freeze-drying, removes water from a peptide solution by freezing it and then lowering the pressure so the ice sublimes directly to vapour. What remains is a dry cake or powder in which the peptide is chemically stable for months to years when kept cold and dark. Every vial on this site ships in this form; the white pellet or powder at the bottom of the vial is the lyophilised peptide, often with a small amount of a bulking agent such as mannitol.

A lyophilised peptide does not degrade the way a solution does because the reactions that damage peptides, hydrolysis and oxidation, need water to proceed. That is why the shelf life of an unopened vial is measured in years and the shelf life of a reconstituted vial in weeks. It is also why a vial that has been through a warm courier depot is usually fine, while a reconstituted vial left on a bench is not.

Handling a lyophilised vial correctly means keeping it refrigerated, keeping the cap on until use, and adding diluent slowly down the side of the glass rather than jetting it onto the powder, which can shear fragile peptides. The cold-chain guide covers storage before reconstitution and the reconstitution guide covers the step itself.