Peptide Reconstitution.

What you need.

• The lyophilized peptide vial (room-temperature, sealed).
• Bacteriostatic water, USP grade, with 0.9% benzyl alcohol preservative.
• Sterile transfer syringe (1mL or 3mL, depending on water volume needed).
• Sterile insulin syringe (U-100, 0.5mL or 1mL) for drawing reconstituted solution.
• Alcohol swabs.
• Clean working surface.

Step-by-step procedure.

1. Allow the sealed peptide vial to reach room temperature, approximately 20 minutes if it has just come out of refrigeration. Cold vials condense moisture during reconstitution.
2. Wipe the rubber stopper of both the peptide vial and the bacteriostatic water bottle with a fresh alcohol swab. Allow to air-dry.
3. Draw the calculated volume of bacteriostatic water into the transfer syringe (see “Concentration math” below).
4. Insert the syringe needle through the rubber stopper of the peptide vial, angled so the water flows down the inside wall of the vial — not directly onto the powder. This minimizes disruption of the lyophilized cake.
5. Inject the water slowly. Withdraw the syringe.
6. Roll the vial gently between your palms for 30–60 seconds. Do not shake. Shaking introduces air and can damage peptide structure.
7. Allow the vial to sit undisturbed for 5–10 minutes for the powder to fully dissolve. The solution should be clear; some peptides are slightly cloudy initially and clear as they dissolve fully.
8. Label the vial with: compound name, concentration in mg/mL, and reconstitution date. Refrigerate at 2–8°C.

Concentration math.

Concentration is mass per volume. A 10mg vial reconstituted with 2mL of bacteriostatic water yields a 5mg/mL solution. A 10mg vial reconstituted with 1mL yields 10mg/mL. A 5mg vial reconstituted with 1mL yields 5mg/mL.

For drawing from a reconstituted vial, the U-100 insulin syringe is the standard tool. U-100 means 100 international units (IU) per 1mL. So 0.1mL on a U-100 syringe equals 10 IU, or one-tenth of the syringe. At a 5mg/mL concentration, 0.1mL contains 0.5mg, which is 500 micrograms (mcg).

Different research applications study different concentrations and volumes. Published research literature on individual compounds documents the concentrations and dose ranges examined in studies; the per-compound product page accordions on this site cite those studies. Our peptide concentration calculator (in development) will provide concentration math for any compound, vial size, and bacteriostatic water volume combination.

Common mistakes.

Common reconstitution errors that compromise integrity:

• Adding water too forcefully — squirts directly onto the lyophilized cake, causing localized denaturation.
• Shaking vigorously — introduces air and can shear peptide bonds.
• Not letting the powder fully dissolve before drawing — produces uneven concentration in subsequent draws.
• Touching the rubber stopper with hands or non-sterile surfaces between draws — introduces contaminants that bacteriostatic water’s preservative cannot fully address over weeks.
• Using non-USP-grade water — sterile saline or distilled water lack the bacteriostatic preservative; reconstituted solutions in these diluents degrade rapidly.
• Reconstituting into a vial showing temperature compromise signs — see the Storage Guide for compromise indicators.

After reconstitution.

Refrigerate the reconstituted vial at 2–8°C immediately. Stability is typically 14–30 days depending on compound — see the Storage Guide for compound-class stability ranges. Always re-swab the rubber stopper with alcohol before each subsequent draw. If multiple researchers will use the same vial over time, label with reconstitution date prominently and check stability against the compound-specific shelf life.