Lyophilization

Lyophilization, or freeze-drying, removes water from a frozen peptide solution under vacuum so the peptide is left as a dry, stable powder.

Research peptides are usually supplied lyophilized: the purified peptide is dissolved, frozen, and held under vacuum so the ice sublimes directly to vapour without passing through a liquid. What remains is a light, often barely visible cake or powder at the bottom of the vial.

The point is stability. Many peptides degrade in solution through hydrolysis, oxidation or aggregation, and removing water slows those reactions. That is why storage guidance for lyophilized material, typically -20 °C, away from light and heat, is far longer than for the same peptide once reconstituted, which is generally kept at 2–8 °C and used within weeks.

Lyophilized does not mean anhydrous. The powder still holds some residual water and readily picks up moisture from the air once the vial is opened, which is one reason the weighed mass of a lyophilized peptide is more than its peptide content. Let a vial reach room temperature before opening it, so condensation does not form on the cold powder.

Related terms

• Net peptide content
• Counter-ion

UPDATED OCTOBER 26, 2026 · REVIEWED BY DEL POTTER, PHD