How to Store Peptides: Complete Storage & Stability Guide

Use this table for fast answers:

General rule: Colder is usually better, but avoid repeated freezing and thawing.

Peptides break down through several processes. Knowing these helps you prevent damage:

Most sensitive amino acids:

Some amino acids are more prone to damage:

• Methionine (Met) – Prone to oxidation
• Cysteine (Cys) – Forms unwanted bonds
• Tryptophan (Trp) – Sensitive to light
• Asparagine (Asn) – Can change structure
• Glutamine (Gln) – Can change structure

Peptides with these amino acids need extra care.

Lyophilised peptides are in their most stable form. Freeze-drying removes water, which greatly slows breakdown.

Sealed, Unopened Vials

Best conditions:

• Temperature: Room temperature to -20°C (freezer)
• Light: Keep in original packaging or dark place
• Humidity: Low humidity area
• Shelf life: 2+ years when stored correctly

Practical tips:

• Store in a cool, dry cupboard for short-term
• Refrigerate or freeze for longer storage
• Keep in original packaging until needed
• Avoid areas with temperature changes (near windows, ovens)

Opened Vials (Before Mixing)

Once you break the seal, even powder peptides need more careful storage:

• Temperature: 2-8°C (refrigerator)
• Light: Keep away from light
• Sealing: Put cap back firmly after each use
• Shelf life: 6-12 months

Why opened vials need the fridge:

Breaking the seal exposes the peptide to moisture in the air, oxygen, and possible contamination. Refrigeration slows all these breakdown processes.

Mixed peptides are much more fragile than powder. Proper storage is essential.

Refrigeration (Standard Method)

For peptides you'll use within 4 weeks:

• Temperature: 2-8°C (standard fridge)
• Location: Back of fridge (most stable temp)
• Avoid: Fridge door (temperature changes)
• Light: Keep away from light
• Shelf life: 28-30 days maximum

Always label your vials with:

• Peptide name
• Date mixed
• Concentration (mg/ml)
• Use-by date (mixing date + 28 days)

Freezing (For Longer Storage)

For peptides you won't use within 4 weeks:

Important: Divide into single-use portions BEFORE freezing.

Why divide first?

Repeated freezing and thawing damages peptides. Each cycle forms ice crystals that harm structure, causes clumping, and reduces effectiveness.

How to freeze correctly:

1. Work out your typical usage amount
2. Divide mixed peptide into single-use portions
3. Use small sterile vials or tubes
4. Label each with contents, date, and concentration
5. Place in freezer at -20°C
6. Use each portion only once

Frozen storage time: 3-6 months (depends on peptide)

Different peptides have different stability. Here's a guide by peptide:

Highly Stable Peptides
These peptides are fairly forgiving:

Check for these warning signs before using any peptide:

Visual Signs

Other Warning Signs

• Strange smell
• Past expiry date
• Known exposure to heat or light
• Uncertain storage history

When in doubt, throw it out. A new vial costs less than compromised research results.

Do:

• Label everything with dates and concentrations
• Use a dedicated fridge area for peptides
• Keep away from food (contamination risk)
• Store at back of fridge (stable temperature)
• Use within recommended timeframes
• Check appearance before each use

Don't:

• Store in fridge door (temperature changes too much)
• Leave mixed peptides at room temperature
• Expose to direct light
• Freeze without dividing first
• Use cloudy or discoloured solutions
• Keep past expiry dates