Peptide storage is easy to get wrong in ways that don’t show up immediately — a compound can degrade for weeks before a result quietly stops being reproducible. Lyophilised and reconstituted peptides have very different storage requirements, and mixing up the rules for each is one of the most common sources of avoidable variability in peptide research. This guide covers both.
Research Use Only: This guide is intended strictly for laboratory research purposes. Nothing in this article should be interpreted as medical, dosing, or usage advice.
Lyophilised (Freeze-Dried) Peptides
In their lyophilised form, most peptides are relatively stable and can typically be stored in a freezer (around -20°C) for long-term storage, or a refrigerator (2–8°C) for shorter periods before use. Some are stable at room temperature for brief transit windows, but that shouldn’t be relied on for storage once a vial has arrived. Across all storage conditions, lyophilised vials should be kept away from direct light and humidity, since both can accelerate degradation over time.
Reconstituted Peptides
Once a peptide has been reconstituted with bacteriostatic or sterile water, it behaves very differently. Reconstituted solutions should be refrigerated (2–8°C), not frozen, and used within the timeframe indicated for that specific compound — refreezing a reconstituted solution can damage the peptide structure through repeated freeze-thaw cycling. As a general rule, most reconstituted peptides research is documented as remaining stable in the fridge for roughly two to four weeks, though this varies by compound and should be checked for the specific peptide in use rather than assumed.
Light and Heat Sensitivity
Peptides are generally sensitive to prolonged light exposure and heat, both of which can break down the peptide bond structure faster than temperature alone would suggest. Amber vials, foil wrapping, or simply storing vials inside a closed fridge drawer rather than on an open shelf all help minimise this. Avoid leaving reconstituted vials out on a bench between uses, even briefly, if consistency matters for the study.
Freeze-Thaw Cycling
Repeatedly freezing and thawing a reconstituted peptide solution is one of the more damaging things you can do to it. Where a study requires portioning a solution into smaller volumes, it’s better to aliquot before freezing lyophilised stock is reconstituted in bulk, rather than freezing and re-thawing a single reconstituted vial multiple times.
Storage Quick Reference
- Lyophilised, long-term: Freezer, around -20°C, protected from light
- Lyophilised, short-term: Refrigerator, 2–8°C
- Reconstituted: Refrigerator, 2–8°C — never re-freeze
- All forms: Keep away from direct light, heat sources, and humidity
For compound-specific reconstitution steps, see our reconstitution guides, which include worked dilution examples and storage notes for individual peptides.
