Reconstituting peptides — complete guide & calculator
Reconstituting a peptide means dissolving a lyophilised (freeze-dried) peptide in a suitable liquid so that it can be used in an in vitro laboratory protocol. This guide describes the standard procedure for Peplife RUO peptides, with a worked example and a calculator to determine the required volume immediately.
Use the calculator below to quickly calculate the concentration and the required volume. The full explanation — the step-by-step guide, storage and the choice of your solvent — can be found underneath. The calculation formulas themselves are worked out in the reconstitution calculation.
This calculator converts volume and concentration for measuring in-vitro working solutions. It does not provide dosing advice.
reconstitution calculation.
Why peptides are supplied freeze-dried
In dry form, a peptide is chemically quiet: the reactions that slowly break it down need water. That is why lyophilisate often keeps for years under cool, dry conditions. Once it is dissolved, the clock starts ticking and the shelf life drops to days to a few weeks. The practical principle: you only dissolve what you need in the short term. More on that in storing peptides & shelf life.
What do you need to reconstitute a peptide?
- Bacteriostatic water (BAC water) — the recommended reconstitution medium for most RUO peptides
- Sterile insulin syringes (U-100, U-50 or U-30)
- Alcohol swabs (70% isopropanol)
- The lyophilised peptide vial
- The reconstitution calculator at the top of this page
Step by step: reconstituting a peptide
Step 1 — Preparation
Let the vial come to room temperature before opening it or inserting a needle. This prevents condensation and temperature shocks that can destabilise the peptide. Work under clean conditions, preferably under a laminar flow hood.
Step 2 — Calculate how much BAC water you need
Determine the desired working concentration for your research protocol and use this formula:
Volume BAC water (ml) = amount of peptide (mg) ÷ desired concentration (mg/ml)
- Example: BPC-157 5 mg vial, desired concentration 1 mg/ml → add 5 ml BAC water
- Example: Ipamorelin 2 mg vial, desired concentration 0.5 mg/ml → add 4 ml BAC water
Use the calculator at the top of this page to calculate this automatically.
Step 3 — Clean the rubber stopper
Clean the rubber stopper of both the peptide vial and the BAC water vial with a fresh alcohol swab. Allow to dry for 30 seconds before inserting the needle.
Step 4 — Add BAC water
Draw up the calculated amount of BAC water into a sterile syringe. Insert the needle through the rubber stopper of the peptide vial. Inject the BAC water slowly along the inner wall of the vial — do NOT aim the liquid directly at the lyophilised powder.
Step 5 — Dissolve
Gently swirl the vial in circular motions until the powder is completely dissolved. NEVER shake — this can denature the peptide and cause bubbles. If the powder does not dissolve completely, let the vial stand for 5-10 minutes at room temperature and swirl again gently.
Step 6 — Inspect the solution
The reconstituted solution should be clear to slightly yellowish, without visible particles or turbidity. A slight colour is normal for some peptides. Do not use the solution if visible particles are present.
Common mistakes
- Spraying directly onto the powder or shaking hard — can damage the peptide.
- Opening a cold vial immediately — condensation moisture accelerates degradation.
- Estimating volume instead of measuring — the concentration is only as reliable as the measured volume.
- Assuming the label mass — use the net peptide content from the CoA for your calculation.
How do you store a reconstituted peptide?
Store the reconstituted vial at 2-4°C (refrigerator) and use within 28 days. For longer storage: aliquot into smaller volumes and store at −20°C. Avoid repeated freeze-thaw cycles. Use empty sterile vials for aliquoting.
Bacteriostatic water or sterile water — which should I use?
Bacteriostatic water (BAC water) contains 0.9% benzyl alcohol as a preservative, allowing multiple withdrawals from a single vial without loss of sterility. This is the recommended medium for reconstituting most RUO peptides.
Sterile ultrapure water contains no preservative and is suitable for single use. Preferably use BAC water for peptides that are withdrawn multiple times.
Quality & purity
Correct reconstitution starts with a pure starting material. Every relevant batch is independently HPLC-tested by an external laboratory; the CoA is publicly verifiable per batch and states the net peptide content. See also why we rejected a batch.
Frequently asked questions about peptide reconstitution
How long does a reconstituted peptide remain stable?
At 2-4 °C usually up to 28 days. Frozen at −20 °C in aliquots considerably longer. This varies per peptide and per solvent used.
Can I reconstitute a peptide with tap water or ordinary water?
No. Use only bacteriostatic water or sterile ultrapure water. Other water contains impurities and micro-organisms that degrade the research material.
More background on the chemistry of peptide solutions can be found in the scientific literature on peptide stability and reconstitution.
All Peplife products are intended exclusively for in vitro laboratory research (Research Use Only) and not for human or veterinary use.