Lyophilized Peptide Storage and Handling in the Laboratory

Most research peptides are supplied as a lyophilized (freeze-dried) powder. Lyophilization removes water, which greatly slows the chemical reactions that degrade peptides. Even so, how a sample is stored and handled has a large effect on how long it stays intact. Below are the practices most laboratories follow.

Storing lyophilized powder

• Short term: refrigerated at 2–8 °C in the original sealed vial.
• Long term: frozen at −20 °C or colder.
• Keep it dry. Moisture is a primary cause of degradation. Keep vials sealed, and store them with a desiccant if possible.
• Protect from light. Store vials in their box or in a dark container, especially peptides containing light-sensitive residues such as tryptophan.

Avoid condensation when opening

A cold vial opened in room air collects condensation, which introduces moisture into the powder. Let the sealed vial reach room temperature before opening it, ideally inside a desiccator.

Storing reconstituted solutions

Once a peptide is dissolved, it becomes far less stable than the dry powder.

• Refrigerate reconstituted solutions at 2–8 °C.
• Avoid repeated freeze-thaw cycles. If a solution must be frozen, divide it into single-use aliquots first.
• Use sterile technique and sterile diluents to reduce the risk of contamination.
• Record the reconstitution date on the vial.

Factors that accelerate degradation

• Oxidation: methionine, cysteine, and tryptophan residues are especially vulnerable.
• Deamidation: asparagine and glutamine residues can degrade over time in solution.
• Hydrolysis: moisture and extremes of pH can break peptide bonds.
• Aggregation: some peptides clump together at high concentrations or after vigorous shaking.

Labeling and documentation

Keep the batch number visible on every vial and aliquot. That number links the sample to its Certificate of Analysis, which you can look up through the Azyrion Labs COA Verification portal.

Related reading: What Is Bacteriostatic Water? and How to Read a Peptide COA.