BAC Water Reconstitution Ratio Chart
Overview
Choosing the correct BAC water volume for reconstitution determines the final concentration of the peptide solution, which directly drives every subsequent dose calculation. The goal is to select a reconstitution volume that produces a concentration yielding practical syringe draw volumes for the intended dose range — not too small (dead volume loss issues) and not requiring multiple draws for a single dose.
Why 1 mg/mL and 2 mg/mL are most common: These concentrations represent the practical sweet spot for most research peptides. At 1 mg/mL, a 250 µg dose requires 25 units on a U-100 syringe (250 µL) — comfortable, precise, and well above dead volume losses. At 2 mg/mL, the same dose requires 12.5 units (125 µL) — compact volume for protocols where injection volume should be minimized, but still well above dead volume threshold. Concentrations above 4–5 mg/mL push doses into the 10–50 µL range where precision errors increase.
Key reconstitution formula:
- Concentration (mg/mL) = Vial mass (mg) ÷ BAC water volume (mL)
- Concentration (µg/µL) = mg/mL (numerically identical — use these interchangeably)
- Draw volume (µL) = Dose (µg) ÷ Concentration (µg/µL)
- Syringe units (U-100) = Draw volume (µL) ÷ 10
Full Reconstitution Ratio Table
Every combination of common vial sizes and BAC water volumes, with resulting concentration in both mg/mL and µg/mL.
| Vial Size | BAC Water Added | Concentration (mg/mL) | Concentration (µg/mL) | Notes |
|---|---|---|---|---|
| 500 µg (0.5 mg) | 0.5 mL (500 µL) | 1 mg/mL | 1,000 µg/mL | Standard — good for small-dose protocols |
| 1 mL | 0.5 mg/mL | 500 µg/mL | Low concentration — larger draw volumes; max dose is 500 µg | |
| 2 mL | 0.25 mg/mL | 250 µg/mL | Very dilute; draw volumes large for typical peptide doses | |
| 2.5 mL | 0.2 mg/mL | 200 µg/mL | Highly dilute; not recommended for 500 µg vial | |
| 3 mL | 0.167 mg/mL | 167 µg/mL | Too dilute for practical use with this vial size | |
| 5 mL | 0.1 mg/mL | 100 µg/mL | Extremely dilute; avoid unless protocol specifically requires | |
| 1 mg | 0.5 mL | 2 mg/mL | 2,000 µg/mL | Concentrated; suitable for small-volume protocols |
| 1 mL | 1 mg/mL | 1,000 µg/mL | Standard concentration — most practical for 1 mg vials | |
| 2 mL | 0.5 mg/mL | 500 µg/mL | Acceptable; larger draw volumes | |
| 2.5 mL | 0.4 mg/mL | 400 µg/mL | Low; consider 1 mL or 2 mL instead | |
| 3 mL | 0.333 mg/mL | 333 µg/mL | Too dilute for most applications | |
| 5 mL | 0.2 mg/mL | 200 µg/mL | Very dilute; not practical for standard doses | |
| 2 mg | 0.5 mL | 4 mg/mL | 4,000 µg/mL | High concentration; precise draw important; small volumes |
| 1 mL | 2 mg/mL | 2,000 µg/mL | Standard — most practical for 2 mg vials | |
| 2 mL | 1 mg/mL | 1,000 µg/mL | Standard; comfortable draw volumes for most doses | |
| 2.5 mL | 0.8 mg/mL | 800 µg/mL | Acceptable; slightly dilute | |
| 3 mL | 0.667 mg/mL | 667 µg/mL | Acceptable but non-round number makes calculation slightly harder | |
| 5 mL | 0.4 mg/mL | 400 µg/mL | Dilute for a 2 mg vial; only if very low doses needed | |
| 5 mg | 0.5 mL | 10 mg/mL | 10,000 µg/mL | Very concentrated; micro-volumes for each dose; precision issues |
| 1 mL | 5 mg/mL | 5,000 µg/mL | Concentrated; 100 µg dose = 20 µL (2 units) — near dead volume threshold | |
| 2 mL | 2.5 mg/mL | 2,500 µg/mL | Good for higher dose protocols (500 µg–2 mg range) | |
| 2.5 mL | 2 mg/mL | 2,000 µg/mL | Standard — excellent balance; 250 µg = 12.5 units | |
| 3 mL | 1.667 mg/mL | 1,667 µg/mL | Non-round; 2.5 mL is more practical | |
| 5 mL | 1 mg/mL | 1,000 µg/mL | Standard — most practical for 5 mg vials at lower doses | |
| 10 mg | 0.5 mL | 20 mg/mL | 20,000 µg/mL | Extremely concentrated; avoid unless specifically required |
| 1 mL | 10 mg/mL | 10,000 µg/mL | High concentration; micro-draws for standard doses; precision issues | |
| 2 mL | 5 mg/mL | 5,000 µg/mL | Standard for 10 mg at higher dose protocols | |
| 2.5 mL | 4 mg/mL | 4,000 µg/mL | Good for 500 µg–2 mg dose range; compact volumes | |
| 5 mL | 2 mg/mL | 2,000 µg/mL | Standard — practical for standard research peptide doses | |
| 10 mL | 1 mg/mL | 1,000 µg/mL | Standard — comfortable draw volumes; good for lower-dose protocols |
Quick Concentration Reference
Lookup table for the most common reconstitution targets — which vial + volume combinations achieve the target concentration.
| Target Concentration | Vial Size + BAC Water to Achieve It |
|---|---|
| 0.5 mg/mL (500 µg/mL) | 500 µg + 1 mL; OR 1 mg + 2 mL; OR 2 mg + 4 mL; OR 5 mg + 10 mL |
| 1 mg/mL (1,000 µg/mL) | 500 µg + 0.5 mL; OR 1 mg + 1 mL; OR 2 mg + 2 mL; OR 5 mg + 5 mL; OR 10 mg + 10 mL |
| 2 mg/mL (2,000 µg/mL) | 1 mg + 0.5 mL; OR 2 mg + 1 mL; OR 5 mg + 2.5 mL; OR 10 mg + 5 mL |
| 2.5 mg/mL (2,500 µg/mL) | 5 mg + 2 mL; OR 10 mg + 4 mL |
| 4 mg/mL (4,000 µg/mL) | 2 mg + 0.5 mL; OR 5 mg + 1.25 mL; OR 10 mg + 2.5 mL |
| 5 mg/mL (5,000 µg/mL) | 5 mg + 1 mL; OR 10 mg + 2 mL |
| 10 mg/mL (10,000 µg/mL) | 5 mg + 0.5 mL; OR 10 mg + 1 mL |
Draw Volume Reference by Concentration
Given a known concentration, what volume (µL) and U-100 syringe units are required to deliver common research doses?
| Concentration | 100 µg dose | 250 µg dose | 500 µg dose | 1 mg dose | 2 mg dose |
|---|---|---|---|---|---|
| 0.5 mg/mL | 200 µL / 20 units | 500 µL / 50 units | 1,000 µL / 100 units | 2,000 µL — not feasible in single draw | 4,000 µL — not feasible |
| 1 mg/mL | 100 µL / 10 units | 250 µL / 25 units | 500 µL / 50 units | 1,000 µL / 100 units | 2,000 µL — not feasible in single draw |
| 2 mg/mL | 50 µL / 5 units | 125 µL / 12.5 units | 250 µL / 25 units | 500 µL / 50 units | 1,000 µL / 100 units |
| 2.5 mg/mL | 40 µL / 4 units | 100 µL / 10 units | 200 µL / 20 units | 400 µL / 40 units | 800 µL / 80 units |
| 4 mg/mL | 25 µL / 2.5 units | 62.5 µL / 6.25 units | 125 µL / 12.5 units | 250 µL / 25 units | 500 µL / 50 units |
| 5 mg/mL | 20 µL / 2 units | 50 µL / 5 units | 100 µL / 10 units | 200 µL / 20 units | 400 µL / 40 units |
| 10 mg/mL | 10 µL / 1 unit | 25 µL / 2.5 units | 50 µL / 5 units | 100 µL / 10 units | 200 µL / 20 units |
Precision threshold: Draws below 50 µL (5 units on U-100) are susceptible to significant proportional error from dead volume, meniscus reading, and syringe marking resolution. For doses requiring draw volumes under 50 µL, consider reconstituting to a lower concentration (add more BAC water) to increase draw volume into the 100–300 µL range where precision is much better.
Solubility Limits
Not all peptides are soluble at all concentrations. Reconstituting to too high a concentration risks incomplete dissolution and aggregated solution, which delivers inconsistent doses and may cause vascular complications if injected.
| Compound | Approximate Solubility Limit in BAC Water | Recommended Max Concentration | Notes |
|---|---|---|---|
| BPC-157 | >10 mg/mL | 5 mg/mL practical limit | Highly water-soluble; rarely a solubility issue; prefer 1–2 mg/mL for practical draw volumes |
| TB-500 | 2–5 mg/mL | 2 mg/mL | Limited solubility; reconstitute slowly and gently; do not exceed 2 mg/mL; may appear slightly cloudy at higher concentrations — discard if cloudy |
| GHK-Cu | >10 mg/mL | 5 mg/mL practical | Highly soluble; copper complex may give slightly blue-green tint — normal |
| CJC-1295 (with DAC) | 2–5 mg/mL | 2 mg/mL | Moderate solubility; reconstitute gently; 2 mg/mL recommended for reliable clarity |
| Ipamorelin | >10 mg/mL | 5 mg/mL practical | Highly soluble pentapeptide; rarely a solubility concern |
| Tesamorelin | 2–3 mg/mL | 2 mg/mL maximum | Sensitive to agitation; reconstitute by gentle swirl only; 1–2 mg/mL per clinical protocol |
| IGF-1 LR3 | 1–2 mg/mL in BAC water; higher in 0.1% acetic acid | 1 mg/mL in BAC water | Limited solubility in pure BAC water; 0.1% acetic acid may improve solubility but alters pH; keep dilute |
| Melanotan II | 1–2 mg/mL after acetic acid initial dissolution | 1 mg/mL in final BAC water solution | Requires acetic acid dissolution first; then dilute to target with BAC water; keep below 1–2 mg/mL for clear solution |
| PT-141 | 2–5 mg/mL after acetic acid dissolution | 2 mg/mL | More soluble than MT-II; same dissolution protocol; 2 mg/mL clear and stable |
| Semaglutide | 1–2 mg/mL | 1 mg/mL | Formulated by manufacturer at 0.68 mg/mL (Ozempic) or higher; do not exceed 2 mg/mL in BAC water reconstitution |
| MOTS-c | 2–5 mg/mL | 2 mg/mL | Good water solubility; short sequence; 2 mg/mL standard |
| Selank / Semax | >5 mg/mL | 2–5 mg/mL practical | Both highly water-soluble; intranasal formulations often 0.1–1% (1–10 mg/mL equivalent) |
| Epitalon | >10 mg/mL | 5 mg/mL practical | Tetrapeptide; very water-soluble; rarely a solubility concern |
Practical Notes on Choosing BAC Water Volume
The Decision Framework
When choosing how much BAC water to add to a vial, work backwards from the intended dose:
- Identify your dose range — what is the smallest and largest dose you will need from this vial?
- Identify your target draw volume — aim for 50–500 µL per injection for best precision
- Calculate required concentration: Concentration = Dose ÷ Target draw volume
- Calculate BAC water volume: BAC water volume = Vial mass ÷ Required concentration
- Verify against solubility limit — ensure your target concentration is below the compound's solubility limit
Example Decision
You have a 5 mg BPC-157 vial. Your intended dose is 250 µg. You want a draw volume of 25 units (250 µL) on a U-100 syringe. Required concentration = 250 µg ÷ 250 µL = 1 µg/µL = 1 mg/mL. BAC water volume needed = 5 mg ÷ 1 mg/mL = 5 mL. Add 5 mL BAC water. Verify: 5 mg ÷ 5 mL = 1 mg/mL — correct. Check against solubility: BPC-157 is soluble well above 1 mg/mL — fine.
Why the 1 mg/mL Standard Exists
1 mg/mL has become the de facto standard concentration for many research peptide protocols because:
- The math is simple: each µL contains exactly 1 µg; each U-100 unit contains 10 µg
- Most research doses fall in the 100–1,000 µg range — yielding practical 100–1,000 µL draws (10–100 units on U-100)
- It is well below the solubility limit for the vast majority of research peptides
- For a 5 mg vial at 1 mg/mL, you need 5 mL BAC water — a clean, round number
When to Use Higher Concentrations (2 mg/mL or 4 mg/mL)
- Protocols where minimizing injection volume is important (e.g., highly water-sensitive sites, animals with small injection tolerance)
- When dosing very frequently and lower total injection volume is desired
- When the available BAC water volume is limited (e.g., only 1 mL BAC water vial available for a 2 mg peptide vial → 2 mg/mL)
Reconstitution Technique with BAC Water
- Do not inject BAC water directly onto the lyophilized peptide cake — inject down the side of the vial
- Gently swirl — never vortex or shake
- If peptide does not dissolve immediately, let it stand refrigerated for 5–15 minutes and swirl again
- If solution remains cloudy or particulate after 30 minutes, the peptide may be insoluble at that concentration or in BAC water — reconsider solvent choice
References
- Sikiric P, Seiwerth S, Rucman R, et al. "Stable gastric pentadecapeptide BPC 157: novel therapy in gastrointestinal tract." Curr Pharm Des. 2011;17(16):1612–1632. PMID: 21548867. PubMed →
- Turner PV, Brabb T, Pekow C, Vasbinder MA. "Administration of substances to laboratory animals: routes of administration and factors to consider." J Am Assoc Lab Anim Sci. 2011;50(5):600–613. PMID: 22330705. PubMed →
- Falutz J, Mamputu JC, Potvin D, et al. "Effects of tesamorelin in HIV-infected patients with abdominal fat accumulation." J Acquir Immune Defic Syndr. 2010;53(3):311–322. PMID: 20101189. PubMed →
- Goldstein AL, Hannappel E, Kleinman HK. "Thymosin beta4: actin-sequestering protein moonlights to repair injured tissues." Trends Mol Med. 2005;11(9):421–429. PMID: 16099219. PubMed →
- Manning MC, Chou DK, Murphy BM, Payne RW, Katayama DS. "Stability of protein pharmaceuticals: an update." Pharm Res. 2010;27(4):544–575. PMID: 20143256. PubMed →