How to Reconstitute Peptides: Lab Arithmetic, Step by Step
Reconstitution means dissolving a lyophilized peptide in a diluent. Concentration = vial mg ÷ diluent mL: 10 mg in 2 mL is 5 mg/mL. Lab-handling steps and FAQs.
What does reconstituting a peptide mean?
Many peptides ship as a lyophilized (freeze-dried) powder because they are more stable dry. Reconstitution dissolves that powder in a known volume of diluent so that amounts can be measured by volume.
How much diluent should I add?
Work backwards from the concentration you need. The arithmetic is the same for any vial size:
| Vial | +1 mL | +2 mL | +3 mL |
|---|---|---|---|
| 5 mg | 5 mg/mL | 2.5 mg/mL | 1.67 mg/mL |
| 10 mg | 10 mg/mL | 5 mg/mL | 3.33 mg/mL |
| 15 mg | 15 mg/mL | 7.5 mg/mL | 5 mg/mL |
| 20 mg | 20 mg/mL | 10 mg/mL | 6.67 mg/mL |
Step by step
1. Record the vial content
Note the labeled mass, or the net peptide content from a lot-specific certificate of analysis if it reports one.
2. Choose the diluent and volume
Pick the diluent your laboratory protocol specifies and decide the volume from the concentration you need: volume = mass ÷ target concentration.
3. Add diluent slowly
Using aseptic technique, run the diluent down the inside wall of the vial rather than onto the powder.
4. Dissolve without shaking
Swirl or roll gently until the solution is clear; vigorous shaking can damage some peptides.
5. Label and store
Label the vial with concentration and date, and store it as the supplier or your protocol specifies.
How do I convert mg to syringe units?
On a U-100 syringe, units = (mg ÷ concentration in mg/mL) × 100. See the units converter.
Frequently asked questions
What does reconstitute mean?
To dissolve a freeze-dried (lyophilized) powder in a liquid diluent so it can be measured by volume.
How much diluent should I add?
That depends on the concentration you need: volume (mL) = vial mass (mg) ÷ target concentration (mg/mL). Adding 2 mL to a 10 mg vial gives 5 mg/mL.
What is bacteriostatic water?
Sterile water containing a preservative, commonly 0.9% benzyl alcohol, used as a multi-use diluent. Your protocol determines the right diluent.
Does adding more diluent change the amount of peptide?
No. It lowers the concentration; the total mass in the vial is unchanged.
Is this guide for human use?
No. It covers laboratory arithmetic and handling. Approved medicines come as finished products with their own instructions.