HBS (HEPES-buffered saline, pH 7.4) recipe
20 mM HEPES, 150 mM NaCl. A phosphate-free physiological buffer for calcium-containing reactions and binding assays such as SPR.
🧮 Volume calculator
| Component | Amount | Final concentration (1X) |
|---|---|---|
| HEPES (free acid) | 2.385 g | 20 mM |
| NaCl | 4.385 g | 150 mM |
| Water (distilled) | to final volume |
Steps
- Dissolve in about 80% of the final volume of water.
- Adjust to pH 7.4 with NaOH.
- Bring to the final volume with water.
- Filter-sterilise through 0.22 µm (do not autoclave). Store at 4 °C.
Good to know
- This is not the 2X HBS (pH 7.05) used for calcium-phosphate transfection.
FAQ
When use HBS instead of PBS?
When you need to add Ca²⁺/Mg²⁺ or phosphate would interfere.
This is a widely used standard composition. Amounts depend on the hydrate form and purity of your reagents — check the formula weight (FW) on the bottle and follow your institution's safety rules and the manufacturers' instructions.