How to reconstitute peptides
A step-by-step laboratory guide to dissolving lyophilized research peptides: what you need, how to add the diluent, how to store the solution, and a calculator for stock concentrations.
The six steps at a glance · 40 seconds · no sound
Why peptides are reconstituted
Most research peptides are supplied lyophilized, or freeze-dried: the water is removed under vacuum, leaving a dry powder or “cake” that is far more stable than a solution. Before use in the lab, the powder is dissolved again in a measured volume of liquid to give a solution of known concentration, called a stock solution. Doing that carefully protects the peptide and keeps the concentration accurate.
Step by step
- Let the vial reach room temperature
Take the vial out of the freezer and leave it closed for 15–20 minutes. Opening a cold vial lets moisture condense on the powder.
- Work out how much diluent to add
Decide the stock concentration your protocol needs and use the calculator below to find the volume. Leave some headspace in the vial.
- Clean the stoppers
Wash your hands, wear gloves and wipe the rubber stoppers of both the peptide vial and the diluent vial with a 70% isopropyl alcohol swab. Let them air-dry.
- Draw up the diluent
Using a new sterile syringe or a sterile pipette tip, draw the calculated volume of bacteriostatic water from its vial.
- Add it slowly down the side
Insert the needle through the peptide vial’s stopper at an angle and let the diluent run slowly down the inside wall of the vial. Do not spray it directly onto the powder.
- Swirl gently; do not shake
Roll the vial between your fingers or swirl it slowly until the powder dissolves. Shaking creates foam and shear that can damage peptides. Most dissolve within a few minutes; some take longer.
- Check the solution
It should be clear, with no particles or cloudiness. Colourless is normal for most compounds; GHK-Cu and KLOW are blue because of their copper.
- Label and refrigerate
Write the compound, concentration and date on the vial and store it at 36–46 °F, protected from light.
Concentration calculator
The concentration of a stock solution is the amount of compound divided by the volume of liquid. Choose a vial or enter your own amount, then either the volume you will add or the concentration you want.
Arithmetic only: concentration = amount ÷ volume. It does not account for the small volume the powder itself adds.
Quick reference
| Amount in vial | Diluent added | Concentration |
|---|---|---|
| 5 mg | 1 mL | 5 mg/mL |
| 5 mg | 2 mL | 2.5 mg/mL |
| 10 mg | 1 mL | 10 mg/mL |
| 10 mg | 2 mL | 5 mg/mL |
| 10 mg | 3 mL | 3.33 mg/mL |
| 30 mg | 3 mL | 10 mg/mL |
| 60 mg | 3 mL | 20 mg/mL |
1 mg/mL is the same as 1,000 µg/mL, or 1 µg per µL. For HCG, which is measured in international units (IU), the same arithmetic gives IU/mL.
Storing reconstituted solutions
- Refrigerate. Keep solutions at 36–46 °F and protected from light.
- Avoid freeze-thaw cycles. Repeated freezing and thawing can degrade peptides. For longer storage, divide the solution into single-use aliquots and freeze them at −4 °F.
- Keep it clean. Swab the stopper before every withdrawal and use a new sterile needle or tip each time.
- Prepare some compounds fresh. NAD+ and glutathione are less stable in solution than as powder, so prepare them close to use.
- Store unopened powder frozen. Lyophilized vials keep best at −4 °F until you need them.
Troubleshooting
| What you see | What to do |
|---|---|
| Powder not dissolving | Give it more time and keep swirling gently. Do not heat it or shake it. Larger fills such as NAD+ 500mg or glutathione 1200mg dissolve more slowly and need more diluent. |
| Foam on top | Usually from adding the diluent too fast or shaking. Let the vial stand in the refrigerator until the foam settles. |
| Cloudy, or particles that do not dissolve | Do not use it. Cloudiness can mean contamination or the peptide coming out of solution. Contact us with the lot number. |
| Blue colour | Normal for GHK-Cu and KLOW: the colour comes from copper. See why GHK-Cu is blue. |
| Diluent pulled back into the syringe | Sealed vials can hold a slight vacuum. Let the diluent flow in slowly and steadily rather than pushing hard. |
Frequently asked questions
What is the difference between bacteriostatic water and sterile water?
Both are sterile water. Bacteriostatic water also contains 0.9% benzyl alcohol, a preservative that suppresses bacterial growth, so a vial can be entered more than once. Plain sterile water has no preservative and is intended for single use.
Can I shake the vial to dissolve the powder faster?
No. Shaking causes foaming and shear forces that can damage or aggregate peptides. Swirl or roll the vial gently and give it time.
How much bacteriostatic water should I add?
It depends on the stock concentration your protocol needs. Divide the amount in the vial by the concentration you want: 10 mg at 5 mg/mL needs 2 mL. The calculator on this page does the arithmetic.
How long does a reconstituted peptide last?
Stability in solution varies by compound. Keep solutions at 36–46 °F, away from light, and avoid repeated freeze-thaw cycles. For longer storage, divide the solution into single-use aliquots and freeze them.
Is this guide for preparing peptides for human use?
No. This guide describes laboratory handling of research materials. Vivid DNA products are sold strictly for research and are not for human or veterinary use.
Research overviews
Research use only. Vivid DNA products are sold strictly for laboratory research. They are not drugs, foods, cosmetics or supplements, are not for human or veterinary use, and are not intended to diagnose, treat, cure or prevent any disease. This guide describes laboratory handling of research materials only.