Peptides are chemically sensitive. How a vial is stored between receipt and use directly affects the purity value obtained from any downstream analytical measurement. The following are widely accepted handling practices for research-grade lyophilised peptides.
Lyophilised (dry) material
In lyophilised form, most research peptides are stable for extended periods when kept dry and cold. Store sealed vials at -20 °C in an environment protected from light and humidity. Vials should be allowed to equilibrate to room temperature before opening to prevent moisture condensation inside the vial.
Reconstituted (in solution) material
Once dissolved, peptides are far less stable. Reconstituted solutions are typically stored at 2–8 °C for short-term use (days to a few weeks depending on sequence) or aliquoted and frozen at -20 °C to -80 °C for longer storage. Repeated freeze-thaw cycles should be avoided — each cycle can introduce measurable degradation.
Reconstitution medium
Bacteriostatic water is a common reconstitution medium in research contexts because the benzyl alcohol content suppresses microbial growth in multi-use vials. Sterile water can be used for single-use preparations. The chosen medium should be documented alongside the batch and date of reconstitution.
Documentation of storage
Storage temperature, date of receipt, date of first opening, and date of reconstitution should be logged at the lab. This information is essential when a result deviates from expectations and the material history needs to be reconstructed.