Lyophilised (freeze-dried) peptides arrive as a delicate powder inside a sealed vial. Before they can be used in research, they need to be reconstituted - dissolved into a liquid solution using bacteriostatic water (BAC water). This guide covers everything you need to do it correctly, safely, and without degrading the compound.
Important: Do not use normal saline or plain sterile water for peptides you plan to store. BAC water's benzyl alcohol content inhibits bacterial growth, keeping your reconstituted solution viable for up to 30 days refrigerated.
Wipe down your work surface with 70% isopropyl alcohol. Allow your peptide vial and BAC water to reach room temperature if they've been stored cold - this takes about 10-15 minutes. Cold BAC water can still be used, but room-temperature water dissolves the powder more evenly.
Swab the rubber stopper of both the peptide vial and the BAC water vial with an alcohol pad. Let them air-dry for a few seconds. This prevents introducing contaminants when you pierce the stopper.
Insert the syringe needle into the BAC water vial and draw out the desired volume. The amount you add determines the concentration of your solution.
Concentration formula: If you add 1 mL of BAC water to a 5 mg peptide vial, each 0.1 mL (10 units on an insulin syringe) contains 0.5 mg (500 mcg). Adding 2 mL would make each 0.1 mL contain 0.25 mg (250 mcg).
Open the Reconstitution Calculator → Enter your vial size, water volume, and desired dose to get exact syringe units.
This is the most critical step. Insert the needle into the peptide vial and aim the stream at the inside wall of the vial, not directly onto the powder. Let the water trickle down the glass slowly. Lyophilised peptides are fragile - a direct jet of water can damage molecular structures and reduce potency.
Once all the water is in the vial, gently roll the vial between your palms or tilt it back and forth slowly. Most peptides dissolve within 30-60 seconds. Never shake the vial - vigorous agitation can denature peptide bonds.
The solution should become clear and colorless. If particles remain after 2-3 minutes of gentle swirling, let the vial sit in the refrigerator for 30 minutes - some peptides take longer to fully dissolve.
Refrigerate the reconstituted vial at 2-8°C (standard refrigerator temperature). Keep it away from light. A reconstituted peptide in BAC water typically remains stable for up to 30 days. For longer storage, some researchers aliquot the solution into smaller vials and freeze them, though freeze-thaw cycles should be minimized.
Use this table for common peptide vial sizes with 1 mL of BAC water added:
| Vial Size | BAC Water Added | Per 0.1 mL (10 IU) |
|---|---|---|
| 2 mg | 1 mL | 200 mcg |
| 5 mg | 1 mL | 500 mcg |
| 5 mg | 2 mL | 250 mcg |
| 10 mg | 1 mL | 1000 mcg (1 mg) |
| 10 mg | 2 mL | 500 mcg |
Both are pharmaceutical-grade water, but they serve different purposes:
For research peptides stored in multi-use vials, BAC water is always the correct choice.
Use the Reconstitution Calculator to see exactly how many units to draw. Then learn how to store and how to inject.
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