How to Reconstitute Lyophilized Peptides? BAC Water and Dose Conversion
Lyophilized powder is the most common peptide format in laboratory and research settings. Get reconstitution or dose conversion wrong and the concentration can be off by an order of magnitude. This page gives calculations you can apply directly.
Basic Concepts
Section titled “Basic Concepts”| Unit | Meaning | Common conversions |
|---|---|---|
| mg | Milligram | 1 mg = 1000 mcg |
| mcg / μg | Microgram | Commonly used for research peptides |
| mL | Milliliter | 1 mL = 100 IU (U100 insulin syringe) |
| IU | Insulin-syringe markings | 100 IU = 1 mL |
Concentration formula:
Concentration (mcg/mL) = total amount (mcg) ÷ reconstitution volume (mL)
Volume to draw:
Volume to draw (mL) = target dose (mcg) ÷ concentration (mcg/mL)
Bacteriostatic Water (BAC Water)
Section titled “Bacteriostatic Water (BAC Water)”BAC water = benzyl alcohol + water for injection, used to inhibit bacterial growth in multi-dose vials. Notes:
- It is not tap water or purified water.
- After opening, store per the instructions and avoid repeatedly contaminating the needle.
- When mixing with powder, inject slowly down the vial wall; avoid vigorous shaking that creates foam.
Calculation Table (Examples)
Section titled “Calculation Table (Examples)”| Total in vial | BAC added | Concentration | Draw for 250 mcg |
|---|---|---|---|
| 10 mg | 2 mL | 5000 mcg/mL | 0.05 mL (5 IU) |
| 10 mg | 5 mL | 2000 mcg/mL | 0.125 mL (12.5 IU) |
| 5 mg | 2 mL | 2500 mcg/mL | 0.1 mL (10 IU) |
| 2 mg | 1 mL | 2000 mcg/mL | 0.125 mL (12.5 IU) |
Procedure
Section titled “Procedure”- Wash hands and clean the work surface; prepare BAC water, a sterile syringe, and alcohol swabs.
- Draw BAC: add the target volume per the table, injecting slowly down the wall of the lyophilized-powder vial.
- Dissolve gently: swirl slowly, do not shake vigorously; most peptides clear within a few minutes.
- Inspect: the solution should be clear with no suspended foreign matter; stop using if it is cloudy or discolored.
- Label: write down the concentration, date, and post-reconstitution storage conditions.
- Draw the dose: draw by IU markings; on an insulin syringe, 100 IU = 1 mL.
Linking to QC and Storage
Section titled “Linking to QC and Storage”For batch purity see COA; for storage after preparation see Storage; for route differences see Bioavailability. For blend specs see Fixed-Ratio Blends.
Methods and Error Control
Section titled “Methods and Error Control”Concentration errors mainly come from insulin-syringe reading precision, reconstitution volume, and residue left on vial walls. Record “total amount, volume, concentration, date”, and cross-check with two independent calculations. Microbial risk in BAC water rises with time after the vial is opened.
Key References
Section titled “Key References”For handling safety and formulation principles see COA and Storage; related delivery research PMID: 37896245.
Related Reading
Section titled “Related Reading”How Much Bacteriostatic Water (BAC) Should I Add?
Section titled “How Much Bacteriostatic Water (BAC) Should I Add?”It depends on the target concentration. With a fixed total amount, less water means a higher concentration; see the table above, and prioritize clear syringe readings.
Why Use BAC Water?
Section titled “Why Use BAC Water?”Repeated draws from a multi-dose vial risk contamination; BAC contains a bacteriostatic agent. It is not purified water.
Key References
Section titled “Key References”Formulation and delivery research: PMID: 37896245, 25384620. For related handling metrics see COA.