Incorrect storage is one of the most common reasons why research peptides lose purity and activity in the laboratory before they ever reach analysis. Peptides are sensitive molecules – heat, light, moisture and mechanical stress can damage their structure. This guide summarises what matters when storing lyophilised and reconstituted peptides.
Why storage matters at all
Peptides consist of amino acid chains linked by peptide bonds. These bonds – and the sensitive side chains of individual amino acids – can be damaged by several processes: hydrolysis (breakdown by water), oxidation (reaction with atmospheric oxygen), photodegradation (damage from UV and light) and microbial growth in aqueous solution. Each of these processes runs faster at higher temperatures and with greater exposure to light and moisture.
Lyophilised (freeze-dried) powder
Peptides are most stable in lyophilised form, because without water most degradation reactions practically come to a halt.
- Unopened, short term: stored at room temperature (up to 25 °C), protected from light and dry, most peptides remain stable for several weeks to months.
- Long-term storage: in the refrigerator (2–8 °C) or – for maximum shelf life over several years – in the freezer at −20 °C.
- Light: keep vials in their original carton or otherwise protected from light, and avoid direct sunlight.
- Moisture: avoid condensation – let vials reach room temperature before opening to prevent moisture getting in.
Reconstituted (diluted) solution
Once a peptide has been reconstituted with bacteriostatic water, its stability drops considerably, because hydrolysis and microbial growth now become possible.
- Refrigerator (2–8 °C): the standard recommendation for reconstituted solutions – usually stable for 4–6 weeks, depending on the peptide.
- Do not freeze after reconstitution: repeated freezing and thawing (freeze-thaw cycles) can damage the peptide structure through mechanical stress at the ice crystal boundaries.
- Protect from light: UV sensitivity remains a factor in solution too.
- Bacteriostatic water as a stabiliser: the benzyl alcohol content (0.9%) of bacteriostatic water inhibits microbial growth in the solution – one reason why it is preferred over plain sterile water for reconstitution.
Signs of quality loss
After incorrect storage, the following changes may indicate a possible loss of quality:
- cloudiness or flocculation of the reconstituted solution (normally clear)
- discolouration of the powder or solution
- unusual odour
When in doubt: a visibly altered solution should no longer be used for research purposes.
Transport and shipping
Lyophilised powder is comparatively robust against short temperature fluctuations during shipping – nevertheless, it is advisable to accept deliveries promptly and not leave them for days in a hot letterbox or in direct sunlight.
Quick overview
| State | Recommended storage | Guideline shelf life |
|---|---|---|
| Lyophilised, unopened | 2–8 °C or −20 °C, protected from light | Several months to years |
| Reconstituted | 2–8 °C, protected from light, do not freeze | approx. 4–6 weeks |
All research peptides mentioned here are available lab-tested and COA-certified in our shop. More on long-term storage in the laboratory: storing research peptides safely.
Note: this article is for information and research purposes only. Research peptides are not intended for human consumption.