Peptide storage

Proper storage is critical to preserving peptide purity, identity, and biological activity over time. The standard recommendation for lyophilised research peptides is -20°C in a sealed glass vial, protected from light and moisture, with a desiccant in the storage container. Under these conditions, most peptides are stable for years (often 2-5 years, with stability data available on COA where measured). For peptides containing residues prone to degradation - cysteine (oxidation of the free thiol), methionine (oxidation to sulfoxide), tryptophan (photo-oxidation), asparagine and glutamine (deamidation), N-terminal glutamine (cyclization to pyroglutamate) - colder storage at -80°C and stricter exclusion of oxygen and light extend shelf life further. Reconstituted aqueous solutions are far less stable than the lyophilised form. The general rule for reconstituted peptides is: use within 28 days at 2-8°C if bacteriostatic water was used, or within 24-48 hours if sterile water without preservative. For long-term storage of reconstituted material, aliquot into single-use volumes and store at -20°C or -80°C; avoid freeze-thaw cycles which cause physical aggregation and chemical degradation. The thumb rule: each freeze-thaw cycle typically reduces peptide integrity by 5-10% depending on the peptide's intrinsic stability. Document storage conditions in the lab notebook - many published papers fail reproducibility audits because storage history is unclear. Peptra Labs ships peptides with peptide-specific storage instructions on each COA and on the peptide hub page; if you're unsure, follow the conservative default (-20°C lyophilised, -80°C reconstituted aliquots) and consult the COA for any peptide-specific deviations.