Peptide Storage Guide — Temperature, Light & Shelf Life

Proper storage is the difference between research-quality peptide solutions and degraded compounds that produce meaningless data. This guide covers storage requirements for both lyophilized (dry) peptide powder and reconstituted peptide solutions.

Storage Requirements by Form

Form	Temperature	Shelf Life	Light
Lyophilized powder (frozen)	-20°C freezer	12–24 months	Protected
Lyophilized powder (refrigerated)	2–8°C fridge	3–6 months	Protected
Reconstituted + BAC water	2–8°C fridge	28 days	Protected
Reconstituted + sterile water	2–8°C fridge	24 hours	Protected

Why Bacteriostatic Water Extends Shelf Life

The 28-day shelf life of a reconstituted peptide with bacteriostatic water (vs 24 hours with sterile water) comes from the 0.9% benzyl alcohol preservative. Benzyl alcohol inhibits bacterial and fungal growth in the vial after each needle puncture. Without it, even careful aseptic technique cannot prevent gradual microbial contamination in a repeatedly accessed vial.

Light Sensitivity

Many peptides contain aromatic amino acids (tryptophan, phenylalanine, tyrosine) that absorb UV light and undergo photodegradation. Store all peptides in amber vials when possible, or wrap clear vials in aluminum foil. Never expose reconstituted peptide solutions to direct sunlight or intense artificial UV sources.

The Freeze-Thaw Problem

Never freeze reconstituted peptide solutions. The freeze-thaw cycle causes: ice crystal formation that physically disrupts peptide tertiary structure, aggregation of denatured peptide molecules, and irreversible loss of biological activity. If you need long-term storage, keep the lyophilized powder frozen and reconstitute fresh batches as needed.

Related: How to Store Reconstituted Peptides (step-by-step) | What Is Lyophilization? | Order BAC Water