How to store research peptides

The short version: keep lyophilised (freeze-dried) peptides sealed, dry, dark and cold, at −20 °C for long-term storage. Once a peptide is in solution it becomes much less stable: keep it at 2–8 °C and use it within the period stated on its certificate of analysis.

That matches the storage line on every JLP certificate: “Lyophilised: −20 °C, protect from light and moisture. Reconstituted: 2–8 °C, use within 28 days.”

Why storage matters

A peptide is a chain of amino acids, and that chain can break down. The main causes are:

• Moisture. Water lets the chain break apart (hydrolysis). Freeze-drying removes the water, which is why the powder form keeps so much better.
• Heat, which speeds up every kind of breakdown.
• Light, especially for peptides containing light-sensitive amino acids such as tryptophan.
• Air. Oxygen can damage peptides containing cysteine, methionine or tryptophan.
• Repeated freezing and thawing of a solution, which stresses the peptide each time.

Any of these lowers purity. A vial that was 99.8% pure on its certificate won’t stay that way if it’s stored badly.

Lyophilised (powder) peptides

• Long term: freezer at −20 °C. Stored this way, sealed and dry, most lyophilised peptides stay stable for a long time.
• Short term: fridge at 2–8 °C is fine for weeks.
• Keep the vial sealed until you need it, in its box or another dark container.
• On arrival: lyophilised peptides generally cope with a few days in the post at room temperature. Put them into cold storage when they arrive.

Opening a vial

The most common mistake is opening a cold vial straight away. Cold glass pulls moisture out of the air, which condenses on the powder.

1. Let the vial reach room temperature before you open it, ideally in a desiccator (a sealed container with a drying agent).
2. Work quickly, take what you need and reseal straight away.
3. Return it to cold storage.

Peptides containing amino acids that attract water (aspartic acid, glutamic acid, lysine, arginine, histidine) are especially prone to picking up moisture, so this step matters more for them.

Peptides in solution

Peptides are far less stable in solution than as powder, so only make up what your work needs.

• Store solutions at 2–8 °C and use them within the time on the certificate (28 days for JLP peptides). Keep the vial sealed and away from light, and not in the fridge door, where the temperature swings.
• Use a sterile solvent and sterile technique. Our bacteriostatic water contains 0.9% benzyl alcohol as a preservative to limit bacterial growth.
• For longer storage, split the solution into single-use portions (aliquots) and freeze them, so each portion is thawed only once.
• Avoid repeated freeze–thaw cycles.
• Slightly acidic, sterile buffers (around pH 5–6) generally keep peptides in solution stable for longer than neutral or alkaline ones.
• Discard a solution that turns cloudy, changes colour or has particles in it.

Quick reference

Form	Where	How long
Lyophilised, sealed	Freezer, −20 °C	Long term
Lyophilised, sealed	Fridge, 2–8 °C	Weeks
Lyophilised, in the post	Room temperature	A few days
In solution	Fridge, 2–8 °C	Up to 28 days (JLP certificates)
In solution, aliquoted	Freezer, −20 °C	Longer, thawed once only

How JLP Labs ships and stores

• Our peptide vials are supplied lyophilised in crimp-sealed glass vials.
• Orders go out in secure, tamper-evident packaging by Royal Mail tracked delivery, dispatched the same day if paid before 13:00 on a working day.
• Each product’s storage conditions are printed on its certificate of analysis.

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