Correct peptide storage determines whether your results will be reproducible. Lyophilized powder, dissolved solution and shipping each have different rules – this overview puts them all in one place.
Peptide storage at a glance
- Lyophilized powder: long term at −20 °C, short term at 2–8 °C.
- Dissolved solution: at 2–8 °C, use within 2–4 weeks; longer only divided into aliquots and frozen.
- Shipping without refrigeration is fine – degradation only starts after dissolving.
- Always protect from light, heat and repeated freezing.
Why peptides are supplied as a powder
Peptides are chains of amino acids joined by amide bonds, which water gradually breaks – a process called hydrolysis. In solution a peptide therefore slowly degrades, whereas lyophilization (freeze-drying) removes the water and immobilises the molecules. As a result, lyophilized powder is much more stable and tolerates shipping without refrigeration; for long-term storage, however, it belongs in the freezer.
How to store lyophilized powder
Store an unopened vial of lyophilized peptide long term in a freezer at −20 °C, where it usually lasts a year or more. For short-term storage (weeks), a laboratory fridge at 2–8 °C is enough. Protect the powder from direct light and moisture – ideally in its original packaging or a dark box, possibly with a desiccant. Before opening a chilled vial, let it come to room temperature so that moisture does not condense on the powder. Repeated thawing and freezing of the powder itself is not a problem, because practically no degradation occurs in the solid state.
How to store a dissolved solution
As soon as you dissolve a peptide in bacteriostatic or sterile water, degradation speeds up. Keep the solution at 2–8 °C, never at room temperature, and use it usually within 2–4 weeks of dissolving – sooner for more sensitive peptides. If you need to keep the solution longer, divide it into aliquots right after reconstitution (ideally into low-protein-binding tubes), freeze them at −20 °C or −80 °C and thaw each aliquot only once. Label every tube with the substance name, concentration, batch number and preparation date. A dissolved peptide cannot be turned back into powder, so dissolve only as much as your experiment plan requires. Our peptide calculator works out the exact concentration after dissolving.
Do peptides survive shipping without refrigeration?
Yes – as long as it is the lyophilized powder and not a dissolved solution. An accelerated stability test of a lyophilized peptide showed that the powder lasts even several days at elevated temperature without a significant loss of purity. That is why we ship peptides as lyophilized powder, not as a ready-made solution. You will find a detailed analysis of the test and other data in the article Do peptides degrade during shipping without refrigeration?
Comparison of storage conditions
| Form | Temperature | Approximate shelf life |
|---|---|---|
| Lyophilized powder (long term) | −20 °C | A year or more |
| Lyophilized powder (short term) | 2–8 °C | Weeks |
| Dissolved solution | 2–8 °C | 2–4 weeks |
| Solution divided into aliquots | −20 °C to −80 °C | Months, thaw each aliquot only once |
| Powder in transit | Room temperature | Days without significant loss of purity |
How to store bacteriostatic water
Bacteriostatic water differs from a peptide in one important way: it contains 0.9% benzyl alcohol, which prevents bacterial growth, so you can draw from one vial repeatedly. An unopened vial lasts up to two years stored cool and dark. After the septum is first pierced, however, it is exposed to air with every draw, so it is recommended to use it within 28 days of first piercing, even though the benzyl alcohol itself degrades more slowly than a peptide in solution.
Why storage affects research results
An incorrectly stored peptide may not smell or look any different, but its actual concentration may be lower than you calculate – whether through degradation from heat, light or repeated freezing of the solution. In an experiment, that means that instead of a substance at the declared concentration you are working with an unknown, lower amount, which undermines the reproducibility of your results. That is why following storage conditions is as important a part of the method as the purity of the starting batch documented by a certificate of analysis.
Common storage and preparation mistakes
- Dissolved solution left out of the fridge – even a few hours at room temperature speed up degradation.
- Shaking the vial vigorously – the solvent should be added slowly down the inside wall, and the vial should only be swirled gently, not shaken.
- Storage in the light – whether powder or solution; both belong in the dark or at least in dark packaging.
- Dissolving a whole vial without an experiment plan – whatever you will not use within 2–4 weeks, divide into aliquots and freeze.
- Unlabelled tubes – without the name, concentration, batch and preparation date, results cannot be traced back.
- Repeatedly freezing an already dissolved solution – unlike the powder, freezing and thawing harms the solution.
Summary
- Store lyophilized powder long term at −20 °C and short term at 2–8 °C.
- Keep a dissolved solution at 2–8 °C and use it within 2–4 weeks; otherwise divide it into aliquots and freeze them.
- Shipping without refrigeration is fine for powder, but not for a solution.
- Always protect from light, label your tubes and dissolve only as much as your experiment plan requires.
Frequently asked questions
How long does a dissolved peptide last?
Usually 2–4 weeks at 2–8 °C. The exact time varies with the specific peptide and the concentration of the solution; divided into aliquots and frozen at −20 °C to −80 °C, it lasts for months.
Do peptides have to be shipped refrigerated?
No, not as a lyophilized powder. It is stable during normal shipping without refrigeration for several days.
Can I refreeze a dissolved peptide?
Once, yes; repeatedly, no. Repeated freezing and thawing of a solution (unlike the powder) speeds up its degradation. That is why the solution is divided into aliquots right after reconstitution and each one is thawed only once.
Why shouldn’t I shake the vial?
Vigorous shaking can damage the peptide’s structure. The solvent should be added slowly down the inside wall of the vial and the peptide left to dissolve with gentle swirling.
How can I tell that a solution has degraded?
You cannot reliably tell by eye – cloudiness or a change in colour may or may not signal degradation. The actual content and purity can only be verified analytically, for example by HPLC. In practice, the safest approach is to stick to the recommended use period and storage conditions from the start.
Need the exact concentration after dissolving? Use our free peptide calculator or have a look at the peptide test results.
The information in this article is for educational purposes only. Jolt Peptides products are intended solely for laboratory research, not for use in humans or animals.