Peptide reconstitution: laboratory practice
A practical guide to dissolving lyophilized peptide for in-vitro work. This is laboratory technique, not medical guidance.
Part of the handling & laboratory practice pillar — the end-to-end chain from receipt to result.
Before you open the vial
- Equilibrate the sealed vial to room temperature (15–30 min).
- Work on a clean bench; wear gloves and eye protection.
- Read the COA for the recommended solvent and any handling notes.
Choosing the solvent
| Peptide type | Typical solvent | Note |
|---|---|---|
| Hydrophilic peptides | Laboratory-grade water | Start with water; add buffer if needed |
| Hydrophobic peptides | Water + acetonitrile or DMSO (small %) | Add organic phase gradually; see DMSO stock solutions |
| Peptides prone to aggregation | Buffer at defined pH | Avoid high concentration stock |
Concentration calculation
Concentration (mg/mL) = mass of peptide (mg) ÷ volume of solvent (mL). For molar concentration, divide by molecular weight: molarity (M) = (mg/mL) ÷ (g/mol) ÷ 1000. Always record the actual mass and volume used — the mass that went in, not the label, which is the point of weighing small peptide quantities. The reconstitution calculator runs the same arithmetic with purity correction, aliquot counting and a dilution step.
Technique
- Add solvent slowly down the vial wall; do not dump it onto the cake.
- Swirl gently — do not vortex, which can shear and cause aggregation.
- Let it stand until dissolved; some peptides need 10–30 minutes.
- Inspect for undissolved particles before use.
If the cake will not wet or the solution stays cloudy, work through solubility troubleshooting before adding heat or filtering.
Storage of solutions
- Aliquot immediately into single-use volumes.
- Short term: 2–8 °C, protected from light — an amber tube or foil wrap, not a clear tube in a lit rack (see light exposure).
- Long term: −20 °C or below; avoid repeated freeze–thaw.
- Record reconstitution date on each aliquot.
Editor's take
Reconstitution is treated as preparation, but it is a measurement. The recorded mass and volume are part of the result, not paperwork around it.
Sources & evidence
- Moisture and particulate methods: USP <731>, <788> — USP.
- Chinese Pharmacopoeia (ChP 2020) Part IV: chapters 0832, 0903 — cited by chapter number.
- Specification/stability concepts: ICH Q6B — ICH.
Laboratory practice guidance; follow your institution's SOPs and the product COA.
Limitations
This is laboratory practice guidance, not a validated stability study. Follow your institution SOPs and the product COA; individual compounds may behave differently.
Products referenced in this guide
Related reading & products
- Research peptide catalogue — 33 documented SKUs
- Measuring peptide concentration — checking what is actually in solution
- Adsorption to labware — why a clear solution can read low
- Filtering solutions — membrane choice, loss and sterility claims
- Peptides in cell-culture assays — preparing a stock that survives medium, plates and incubation
- Buffer selection — pH versus pI, buffer pKa and detection compatibility
- Wholesale & bulk supply — MOQ, tiers and documentation
- Quality framework — how batches are released
- Lab safety and spill response — sharps and spill cleanup during reconstitution
- All knowledge guides