Lyophilized peptide powder is hygroscopic. Storage at -20°C in a sealed, desiccated container is standard laboratory practice. Repeated freeze-thaw cycles introduce moisture and cause aggregation, which shows up as reduced purity on a later analytical run. Where material is reconstituted for bench work, aliquot before freezing and record the reconstitution date alongside the batch number so the analytical history stays complete.
This article is for scientific reference only. Not medical advice. Products mentioned are laboratory research materials and not for human use.