How to reconstitute a lyophilized peptide: complete guide
Bacteriostatic water, dilution volumes, calculations in U-100 units and sterility rules: everything you need to master to reconstitute your research peptides with complete scientific rigor.
Why are research peptides lyophilized?
La freeze-drying (Freeze-drying) is the low-temperature, vacuum-assisted dehydration process that transforms the peptide into a stable powder. This form offers several key advantages for research:
- Long-term stability: A properly stored lyophilized peptide can be kept for 12 to 24 months at room temperature, compared to a maximum of 4 to 6 weeks in aqueous solution.
- No degradation by water: Hydrolysis, the main cause of peptide degradation, cannot occur without a solvent.
- Easy transport: The dry form is more resistant to temperature variations during delivery.
- Precise dosage: The freeze-dried powder is generally packaged with a precise quantity (5 mg, 10 mg, 20 mg) measured by analytical weighing.
Reconstruction is the step that consists of add a sterile solvent to the powder to obtain an injectable solution or one usable in a protocol. This is a critical step: a volume error will invalidate all subsequent assays.
The information in this guide relates exclusively to the handling of peptides. for scientific research purposes in the laboratoryNo information provided constitutes medical advice. MyPeptide.eu peptides are not approved for human or animal use.
The necessary equipment before starting
Before any reassembly, gather all the materials on a clean and disinfected surface. Improvisation during handling is the primary cause of error and contamination.
| Material | Recommended specification | Essential |
|---|---|---|
| Bacteriostatic water (BAC) | USP grade, 0.9% benzyl alcohol | ✓ Yes |
| U-100 Insulin Syringes | 1 ml, graduated 0-100 units | ✓ Yes |
| Needles | 29G or 30G × 8 mm | ✓ Yes |
| Isopropyl alcohol 70% | Sterile wipes or cotton | ✓ Yes |
| lyophilized peptide vial | MyPeptide — verified COA | ✓ Yes |
| Calculator | Or our online calculator | Recommended |
| Label + marker | To note the date and concentration | Recommended |
| Refrigerator 2-8°C | For post-reconstitution conservation | ✓ Yes |
Step 1 — Choosing the right solvent
Bacteriostatic water (BAC): the standard
L’bacteriostatic water USP It contains 0.9% benzyl alcohol, an antimicrobial preservative that slows bacterial growth in the reconstituted vial. It is the solvent of choice for almost all research peptides for two reasons:
- It allows for preservation 28 to 30 days in the refrigerator after reconstitution (compared to a maximum of 5-7 days with plain sterile water).
- It is compatible with 29-30G caliber insulin syringes without risk of clogging.
Sterile water for injection (WFI) is preservative-free. It is suitable if the vial is used for a single procedure. For any procedure involving multiple samples from the same vial, sterile water for injection (BAC) is mandatory. Tap water, non-sterile distilled water, and physiological saline are not suitable for research peptides.
Special cases: peptides requiring a co-solvent
Some poorly water-soluble peptides require initial dissolution in a co-solvent before final dilution in water (BAC):
- Diluted acetic acid (0.6%): for basic peptides (e.g., CJC-1295 without DAC, some GHRPs).
- DMSO ≤ 10%: for highly lipophilic peptides — rare use in standard peptide research.
Consult the MyPeptide product sheet for your peptide to find the recommended solvent. If in doubt, contact our scientific team at science@mypeptide.eu.
Step 2 — Calculate the volume of solvent to add
This is the step most often executed incorrectly. The volume of BAC to be injected into the vial directly determines the final concentration of your solution.
The basic formula
Concentration (mg/ml) = Amount of peptide (mg) ÷ Volume of solvent added (ml)
Example: 10 mg of peptide + 1 ml of water BAC = 10 mg/ml
Convert to U-100 syringe units
U-100 insulin syringes are graduated from 0 to 100 units, i.e. 1 ml total = 100 unitsEach unit = 0.01 ml.
To calculate the volume to be taken per dose:
Units to be taken = (Desired dose in mg ÷ Concentration mg/ml) × 100
Example: target dose = 0.5 mg · concentration = 10 mg/ml
→ (0.5 ÷ 10) × 100 = 5 units on the syringe
| Peptide (10 mg) | BAC added | Concentration | Dose 0.25 mg | Dose 0.5 mg | Dose 1 mg |
|---|---|---|---|---|---|
| 10 mg | 1 ml | 10 mg/ml | 2.5 units | 5 units | 10 units |
| 10 mg | 2 ml | 5 mg/ml | 5 units | 10 units | 20 units |
| 10 mg | 5 ml | 2 mg/ml | 12.5 units | 25 units | 50 units |
| 10 mg | 10 ml | 1 mg/ml | 25 units | 50 units | 100 units |
Choose a concentration that yields whole numbers of units for your usual dose. This reduces reading errors on the syringe. For a 10 mg peptide used in 0.5 mg doses, 1 ml of BAC (→ 5 units per dose) is often the best configuration.
Step 3 — Reconstitution Protocol (sterile procedure)
Prepare your workspace
Disinfect the surface with 70% isopropyl alcohol. Wash your hands thoroughly or wear nitrile gloves. Remove the peptide vial from the refrigerator and allow it to return to room temperature (10-15 minutes) before handling.
Disinfect the bottle caps
Clean the rubber stopper of the peptide vial et Use a bottle of BAC water with an alcohol wipe. Let it dry for 30 seconds — do not blow on or touch the surface after disinfection.
Vacuum the calculated volume of the bin
Using a new sterile syringe, draw up the volume of bacteriostatic water calculated in step 2 (e.g., 1 ml). Remove any air bubbles by gently tapping the syringe and slightly pushing the plunger upwards.
Inject the BAC into the peptide vial — gently
Insert the needle at a 45° angle into the rubber stopper of the vial. Do not inject directly onto the powder. Direct the flow onto the glass wall for gentle dissolution. Inject slowly, avoiding any foam formation (foam denatures peptides).
Mix by rotation — never by shaking
Gently rotate the vial between your palms for 30 to 60 seconds until the powder is completely dissolved. Never vortex or shake vigorously — this would break up the peptide chains. If lumps persist, let it rest for 2-3 minutes and then repeat the rotation.
Check for dissolution and label
The solution should be clear, colorless or slightly yellowish depending on the peptide, without visible particles. Immediately label the vial with the reconstitution date, the peptide, and the concentration (e.g., "CJC-1295 · 10 mg/ml · 01/05/2024").
Store in the refrigerator immediately
Place the reconstituted vial in the refrigerator at 2-8°C, protected from light (in its original container or wrapped in aluminum foil). The solution can be stored for a maximum of 28 days with BAC water, and 5-7 days with plain sterile water.
Tips to avoid the most common mistakes
✅ To do
- Use a new, sterile syringe for each sample.
- Gently turn the vial to mix
- Inject the BAC onto the vial wall
- Label with date and concentration
- Check for clarity before use
- Store away from light
❌ To be avoided
- Shake or vortex the vial
- Inject directly onto the powder
- Leave at room temperature after reconstitution
- Reuse the same syringe several times
- Use tap water or non-sterile distilled water
- Freeze/thaw several times
Storage and shelf life after reconstitution
The reconstituted peptide is much more fragile than in lyophilized form. Degradation factors include heat, UV light, oxidation by dissolved oxygen, and bacterial contamination.
| Solvent used | Temperature | Maximum duration | Remarks |
|---|---|---|---|
| BAC water (0.9% benzyl alcohol) | 2-8°C (refrigerator) | 28 days | Recommended standard |
| Simple sterile water | 2-8°C | 5-7 days | No preservatives |
| Water TAN | -20°C (freezer) | 3-6 months | Avoid freeze/thaw cycles |
| Any solvent | Room temperature | < 24h | Not recommended |
Some peptides tolerate freezing at -20°C, while others are damaged by the formation of ice crystals. If in doubt, prepare aliquots of precise volumes (e.g., 5 individual samples frozen separately) rather than freezing/thawing the main vial multiple times.
Reconstruction calculator
Enter the peptide quantity and BAC volume to instantly obtain the concentration, the volume to be taken per dose, and the number of doses available in the vial.
Reconstruction calculator
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