How a freeze-dried peptide is reconstituted in the lab

Before you start

Work on a clean, dry surface and wear gloves. Let both the peptide vial and the diluent come to room temperature first. A cold vial taken straight from the fridge collects condensation on the outside and is harder to handle safely.

Read the label so you know the compound, the strength in milligrams, and what your protocol says about the diluent and the final concentration. The protocol, not this article, decides the volume.

The steps

1. Wipe the rubber stopper of the peptide vial, and of the diluent vial, with an alcohol swab and let it dry.
2. Draw up the volume of diluent your protocol calls for using a clean, sterile syringe.
3. Add the diluent slowly, letting it run down the inside wall of the vial instead of hitting the powder directly.
4. Swirl the vial gently or roll it between your fingers. Do not shake it. Shaking makes the liquid foam and can damage a delicate peptide.
5. Wait until the liquid is completely clear. A few minutes is normal. If it stays cloudy or you can see particles, do not use it, and note the batch in your records.
6. Label the vial with the date, the diluent used and the final concentration.

Why the diluent matters

Plain sterile water has no preservative, so a vial made up with it is meant to be used once. Bacteriostatic water contains a small amount of benzyl alcohol, a preservative, which is why laboratories choose it for a vial that will be opened more than once. Our post on bacteriostatic water explains the difference in more detail.

After reconstitution

Once dissolved, a peptide is much less stable than the dry powder. Keep the vial cold and out of the light, avoid repeated freezing and thawing, and use it within the time your protocol allows. Our post on storing vials covers the details.

Research use only

Pep Pantry products are sold for laboratory research by adults. They are not for human or veterinary use. This article describes laboratory handling only.