The complete beginner’s guide: every research peptide arrives as a small puck of white (or blue) powder at the bottom of a vial. Turning that powder into an accurate, stable solution is the single most important step in working with peptides, and the one most people get wrong. This guide walks through it from start to finish: what reconstitution is, which diluent to use, the exact lab procedure, how to calculate concentration for every common vial size, how to fix cloudy or stubborn vials, and how to store the result.
Shortcut: skip the arithmetic with our free peptide reconstitution calculator, which converts mg, mL and mcg into concentration and volume.
What reconstitution actually means
Peptides are shipped lyophilized, or freeze-dried. During manufacturing, the purified peptide is dissolved, frozen and placed under vacuum so the water sublimates straight from ice to vapour. What is left is a dry, porous cake that is far more stable than any solution: water drives most of the chemical reactions that degrade peptides, so removing it buys months or years of shelf life.
Reconstitution is simply reversing that process in the lab: adding a known volume of a suitable liquid so the peptide dissolves into a solution of known concentration. Two things matter: that the peptide dissolves completely without being damaged, and that you know exactly how much peptide is in each millilitre afterwards.
Why the vial looks almost empty: a 5 mg peptide cake is tiny, and sometimes it is a thin film rather than a visible puck. That is normal. What matters is the mass on the label and the COA, not how full the vial looks.
Choosing a diluent: bacteriostatic vs sterile water
| Bacteriostatic water | Sterile water | Dilute acetic acid (0.6–1%) | |
|---|---|---|---|
| What it is | Sterile water + 0.9% benzyl alcohol | Sterile water, no preservative | Weak acid solution |
| Best for | Multi-use vials accessed over days or weeks | Single-use preparations | Hydrophobic peptides that resist water |
| Microbial protection | Yes, inhibits growth | None once opened | Some |
| Typical use with peptides | The default choice | When a protocol forbids preservatives | Specialist cases only |
For the vast majority of research peptides, bacteriostatic water is the standard. The benzyl alcohol keeps bacteria from multiplying each time the septum is punctured, which matters because most labs draw from the same vial many times. Never use tap water, distilled water from a store or saline unless a specific protocol calls for it.
What you need on the bench
- The peptide vial, brought to room temperature (still sealed)
- A vial of bacteriostatic water
- Isopropyl alcohol swabs (70%)
- A sterile, single-use measuring and transfer tool sized for the volume you need (a calibrated sterile syringe or pipette)
- Nitrile gloves and a clean, wiped-down work surface
- A label and a fine-tip marker
- A sharps or biohazard container for disposal
The 8-step reconstitution procedure
- Equilibrate. Take the peptide and diluent out of cold storage and let them reach room temperature, unopened, for 15 to 30 minutes. Opening a cold vial makes moisture condense on the powder.
- Prepare the area. Wipe the bench, wash hands and put on gloves.
- Remove the caps from both vials and swab each rubber septum with a fresh alcohol swab. Let the alcohol evaporate for a few seconds.
- Measure the diluent. Using a new sterile transfer tool, draw the exact volume of bacteriostatic water you have chosen (see the tables below).
- Add it slowly, down the glass. Insert through the septum at an angle and let the water run gently down the inside wall of the vial. Never jet it directly onto the powder: the force can shear fragile peptides and cause foaming.
- Swirl, don’t shake. Gently roll the vial between your fingers or swirl it in small circles. Most peptides dissolve within one to two minutes.
- Inspect. The solution should be clear and free of particles (copper peptides will be clear blue). If anything remains undissolved, let it rest in the fridge for 10 to 15 minutes and swirl again.
- Label and store. Write the compound, concentration, lot number and date on the vial, then refrigerate at 2–8 °C.
Concentration math, made simple
There is only one formula you need:
Concentration (mg/mL) = peptide mass (mg) ÷ diluent volume (mL)
Add 2 mL of water to a 10 mg vial and you have 5 mg/mL. Add 1 mL and you have 10 mg/mL. That’s it. Two unit conversions make lab work easier:
- 1 mg = 1,000 µg (micrograms), so 5 mg/mL is the same as 5,000 µg/mL.
- 1 mg/mL = 1 µg/µL, which is handy when you work with micropipettes in microlitres.
How to pick a volume: more diluent gives a more dilute solution, which is easier to measure accurately in small aliquots. Less diluent gives a concentrated stock that takes less fridge space. Many labs choose a volume that produces a round number (1, 2, 5 or 10 mg/mL) so that every later calculation is simple.
Concentration tables for every vial size
Standard vials (2, 5 and 10 mg)
Applies to BPC-157, TB-500, Ipamorelin, CJC-1295, Tesamorelin and others.
| Vial | + 1 mL | + 2 mL | + 3 mL | + 5 mL |
|---|---|---|---|---|
| 2 mg | 2 mg/mL | 1 mg/mL | 0.67 mg/mL | 0.4 mg/mL |
| 5 mg | 5 mg/mL | 2.5 mg/mL | 1.67 mg/mL | 1 mg/mL |
| 10 mg | 10 mg/mL | 5 mg/mL | 3.33 mg/mL | 2 mg/mL |
| 20 mg | 20 mg/mL | 10 mg/mL | 6.67 mg/mL | 4 mg/mL |
Large vials (50 to 100 mg)
Applies to GHK-Cu, AHK-Cu, Epithalon (50 mg), SS-31 (50 mg) and blends like GLOW70 and KLOW80.
| Vial | + 2 mL | + 5 mL | + 10 mL |
|---|---|---|---|
| 50 mg | 25 mg/mL | 10 mg/mL | 5 mg/mL |
| 70 mg (GLOW) | 35 mg/mL | 14 mg/mL | 7 mg/mL |
| 80 mg (KLOW) | 40 mg/mL | 16 mg/mL | 8 mg/mL |
| 100 mg | 50 mg/mL | 20 mg/mL | 10 mg/mL |
For blends, each component has its own concentration. In a GLOW vial (GHK-Cu 50 mg + BPC-157 10 mg + TB-500 10 mg) reconstituted with 5 mL, GHK-Cu is at 10 mg/mL while BPC-157 and TB-500 are each at 2 mg/mL. Always calculate per component.
NAD+ (100 to 1000 mg)
| Vial | + 5 mL | + 10 mL |
|---|---|---|
| 100 mg | 20 mg/mL | 10 mg/mL |
| 500 mg | 100 mg/mL | 50 mg/mL |
| 1000 mg | 200 mg/mL | 100 mg/mL |
Large NAD+ vials need larger diluent volumes to dissolve fully; a 10 mL bacteriostatic water vial is the practical choice.
Troubleshooting: cloudy, foamy or undissolved
| Problem | Likely cause | What to do |
|---|---|---|
| Foam on top | Diluent added too fast or vial shaken | Let it settle in the fridge; foam usually collapses. Swirl gently next time. |
| Powder stuck to the walls | Cake dislodged in transit | Tilt and roll the vial so the liquid washes the walls. |
| Slightly hazy | Not fully dissolved yet, or cold diluent | Rest 10–15 minutes, swirl again. |
| Stays cloudy or has particles | Hydrophobic peptide, aggregation or contamination | Do not use. Contact the supplier with the lot number. |
| Wrong colour | Possible degradation or wrong compound | Copper peptides should be blue; most others clear. Contact the supplier. |
Compound-specific notes
| Compound | What to know |
|---|---|
| GHK-Cu / AHK-Cu | Dissolves to a clear blue. Avoid buffers containing chelators (EDTA) or strong reducing agents, which strip the copper. |
| NAD+ | Very hygroscopic: work quickly once opened. Less stable in solution than as powder, especially at alkaline pH. |
| BPC-157 | Dissolves easily and is unusually stable for a peptide. |
| CJC-1295 with DAC | Larger peptide; give it a little extra time to dissolve fully. |
| Tirzepatide (TZ-2) | Large, lipidated peptide. Add diluent slowly and allow extra time; never shake. |
| HCG | A glycoprotein measured in IU; keep refrigerated rather than repeatedly frozen. |
| Blends (GLOW, KLOW) | Calculate the concentration of each component separately. |
After reconstitution: storage and shelf life
- Refrigerate at 2–8 °C, upright, away from light.
- Use bacteriostatic water for multi-use vials; solutions made with plain sterile water should be treated as single-use.
- Avoid freeze-thaw cycles. If a stock must be frozen, divide it into single-use aliquots first.
- Shelf life is shorter than powder. Exact stability depends on the peptide; most labs plan to use reconstituted stock within a few weeks.
- Unopened powder stays in the freezer until needed. Only reconstitute what you will use.
The full science of degradation is in how to store peptides.
The 10 most common reconstitution mistakes
- Opening the vial while it is still cold.
- Squirting diluent straight onto the powder.
- Shaking the vial to speed things up.
- Using tap, distilled or bottled water.
- Reusing a transfer tool between vials.
- Skipping the alcohol swab on the septum.
- Not writing the concentration on the label.
- Forgetting that blends have several concentrations, one per component.
- Leaving the reconstituted vial at room temperature.
- Freezing and thawing the same vial repeatedly.
Frequently asked questions
Cliquez sur une question pour afficher la réponse.
What is the best liquid to reconstitute peptides?
Bacteriostatic water (sterile water with 0.9% benzyl alcohol) is the standard for multi-use laboratory vials. Sterile water works for single-use preparations; dilute acetic acid is reserved for hydrophobic peptides that resist water.
How do I calculate peptide concentration?
Divide the peptide mass in mg by the volume of diluent in mL. For example, 10 mg in 2 mL gives 5 mg/mL.
Should I shake a peptide vial to dissolve it?
No. Shaking can damage peptides and cause foaming. Swirl or roll the vial gently and let it rest if needed.
Why is my reconstituted peptide cloudy?
Slight haze usually clears with rest and gentle swirling. Persistent cloudiness or particles can mean aggregation or contamination; do not use the vial and contact the supplier.
How long does a reconstituted peptide last?
It depends on the compound, but reconstituted peptides are far less stable than powder. Keep them refrigerated, protected from light, and plan to use them within a few weeks.
How much bacteriostatic water do I need?
Typically 1 to 3 mL for 2–10 mg vials and 5 to 10 mL for 50–100 mg vials or NAD+. A 10 mL vial covers several peptide vials.
Related reading
- How long does BPC-157 take to work?
- How long does reconstituted BPC-157 last?
- How to store peptides: 6 mistakes to avoid
- How to read a peptide COA
- Peptides 101: beginner’s guide
- Wolverine vs GLOW vs KLOW
This guide describes laboratory handling of research compounds. All TrueLabs products are sold for in vitro and laboratory research use only. They are not intended for human or veterinary use, and nothing in this article is medical advice or instructions for administration.