Storage starts the moment a parcel is opened

Correct dispatch and packaging only protects a sample up to the point of delivery. What happens in the next few minutes — and over the following weeks — determines whether that sample still matches its certificate of analysis when it's actually used in research. Peptides are structurally fragile molecules, and poor storage is one of the most common (and most avoidable) causes of degraded results.

Lyophilised vs reconstituted: different rules apply

Most research peptides are supplied as a lyophilised (freeze-dried) powder, which is significantly more stable than a reconstituted solution. The two states have different storage requirements:

Lyophilised (powder) form:

• Store in a standard refrigerator (2–8°C) for short-to-medium term stability, or a freezer (-20°C or below) for longer-term storage.

• Keep vials in their original packaging, away from direct light — UV and even prolonged ambient light exposure can degrade peptide bonds over time.

• Avoid repeated temperature cycling. Moving a vial in and out of the fridge repeatedly introduces condensation risk once the seal is broken, and thermal cycling generally is harder on stability than a single, consistent storage temperature.

Reconstituted (liquid) form:

• Reconstituted peptides are considerably less stable than lyophilised powder and should be refrigerated at all times.

• Shelf life drops sharply once reconstituted — typically to a matter of weeks even under correct refrigeration, compared to months or longer for the unreconstituted powder.

• Label reconstituted vials with the date of reconstitution so degradation timelines can be tracked accurately against research data.

Why light exposure matters more than researchers often expect

Peptide bonds are susceptible to photodegradation, and this is one of the more underestimated storage risks. A vial left on a windowsill or under direct lab lighting for extended periods can degrade meaningfully faster than one stored in the dark, even at the correct temperature. Amber vials and opaque outer packaging exist for a reason — if a vial has been decanted or repackaged, keeping it in a closed drawer or box rather than an open shelf is a simple way to control for this variable.

Realistic shelf-life expectations

Shelf life depends heavily on the specific compound, but as a general reference point:

• Unreconstituted, correctly stored (frozen): typically 12–24 months, though this varies by peptide.

• Unreconstituted, refrigerated: typically several months.

• Reconstituted, refrigerated: typically 2–4 weeks, sometimes less depending on the compound and buffer used.

These figures are general guidance rather than a substitute for compound-specific data — the certificate of analysis supplied with each order is the definitive reference for a given batch, and any storage recommendations specific to a compound are noted there. If a COA wasn't included or needs clarifying, our contact page is the fastest route to get one confirmed.

Building storage checks into lab intake

A short, consistent intake procedure avoids most storage-related issues:

1. Check the vial immediately against the checks outlined in our dispatch and packaging guide.

2. Transfer to correct storage (fridge or freezer) without delay — don't let a parcel sit on a bench "until later."

3. Log the storage start date and location per vial or batch.

4. Keep lyophilised stock separate from any reconstituted solutions to avoid mix-ups on inventory checks.

More general handling questions are also covered in our FAQ section, and the full range of compounds — each supplied with a certificate of analysis — is available across our catalogue.

All products supplied by Stack Peptides are intended strictly for laboratory and scientific research purposes. Not for human or veterinary use.