Lyophilized Peptide Stability: A Laboratory Handling Primer

Lyophilization — freeze-drying under vacuum — removes water from a peptide solution while leaving the peptide structure intact. The result is a porous, amorphous cake that can be stored for extended periods with minimal degradation.

Why lyophilized peptides are stable

Most peptide degradation pathways (hydrolysis, deamidation, oxidation, aggregation) require water or dissolved oxygen. Removing bulk water dramatically slows these reactions. Under proper storage — sealed vial, -20°C, protected from light — most research peptides retain their stated purity for 24 months or longer.

What changes at reconstitution

Adding bacteriostatic water restarts every degradation clock. Practical guidance:

• Refrigerate reconstituted material at 2–8°C.
• Avoid repeated freeze/thaw cycles.
• Use within 4–6 weeks for most sequences; shorter for oxidation-prone residues (Met, Cys, Trp).
• Bacteriostatic water is preferred over sterile water because the low benzyl alcohol concentration suppresses microbial growth in a multi-use vial.

The label always wins

Manufacturer-specific stability windows on the COA supersede general guidance.