Reconstituting and storing peptides, step by step

A maximum-purity peptide degrades if reconstituted or stored badly. This guide sums up standard research practice so you don't ruin a good vial.

Before you start

The peptide arrives lyophilised (powder) under vacuum. Let it equilibrate to room temperature before opening the vial, to avoid condensation that introduces moisture. Work on a clean surface with aseptic technique.

The right solvent

The standard is bacteriostatic water (water with 0.9% benzyl alcohol), which inhibits bacterial growth and keeps the solution stable for days. Plain sterile water works for immediate use but does not preserve. Never use tap or non-sterile distilled water.

How to reconstitute without damaging the peptide

Draw the solvent with a sterile syringe and let it run down the inner wall of the vial in a slow drip, not directly onto the powder. Do not shake: swirl gently until dissolved. Vigorous shaking and foam can denature the peptide.

Concentration calculation

Concentration depends on the solvent you add. Example: 5 mg of peptide in 2 ml of bacteriostatic water = 2.5 mg/ml. A reconstitution calculator avoids errors; many serious vendors publish one.

Storage

Sealed lyophilised powder: stable for months at room temperature protected from light, better refrigerated. Reconstituted solution: in the fridge at 2-8 °C, use within a few weeks; for the long term, frozen aliquots at -20 °C or -80 °C. Avoid freeze-thaw cycles: each cycle degrades the peptide.

Signs something is wrong

Persistent cloudiness, particles that won't dissolve, or a colour change can indicate degradation or contamination. Always label the vial with compound, concentration, reconstitution date and lot.