⚗️ Buffer Recipe Calculator
Precision is key. Standard recipes for SPR and BLI running buffers. Calculations use accurate molecular weights for standard lab salts (e.g., EDTA disodium dihydrate).
Running buffer = sample buffer. Always dilute your analyte into the same buffer used for the run — matched ionic strength, surfactant, and DMSO content are critical for clean kinetics.
Standard Biacore running buffer. Good for general protein interactions.
HBS-EP+
Target pH: 7.4| Reagent | Amount |
|---|---|
HEPES MW: 238.30 g/mol | 2.38 g |
NaCl MW: 58.44 g/mol | 8.77 g |
EDTA (Disodium) MW: 372.24 g/mol | 1.12 g |
Surfactant P20 / Tween 20 From 10% Stock Solution (prepare: 10 g Tween 20 + water to 100 mL) | 5.00 mL |
Preparation Steps:
- Dissolve reagents in approx 800 mL of ultrapure water (80% of final vol).
- Adjust pH to 7.4 using NaOH.
- Cytiva Surfactant P20 is a polysorbate-20 formulation; generic Tween 20 (polysorbate 20) is an acceptable substitute.
- Add water to final volume of 1000 mL.
- Filter through 0.22 µm membrane. Degas if using for SPR.
Common Regeneration Buffers
💡 Key principle: For acid regeneration (glycine), pH dominates over buffer concentration. For chaotropes (guanidine-HCl) and detergents (SDS), concentration is the primary variable — 6 M GuHCl is far harsher than 1 M. Start mild, increase harshness only if needed.
| Buffer | Recipe | Harshness |
|---|---|---|
| Glycine-HCl pH 2.0 | 10 mM glycine + HCl to pH 2.0 | |
| Glycine-HCl pH 1.5 | 10 mM glycine + HCl to pH 1.5 | |
| NaOH 10 mM | 10 mM NaOH in water | |
| NaOH 50 mM | 50 mM NaOH in water | |
| NaCl 1–2 M | 1–2 M NaCl in running buffer | |
| MgCl₂ 1–4 M | 1–4 M MgCl₂ in water (antibody / electrostatic capture surfaces) | |
| 6M Guanidine-HCl | 6 M guanidine hydrochloride in water | |
| 0.1% SDS | 0.1% (w/v) sodium dodecyl sulfate in water |
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