Church hybridisation buffer recipe
A formamide-free hybridisation buffer for Southern and Northern blots: 0.5 M sodium phosphate pH 7.2, 7% SDS, 1 mM EDTA, 1% BSA.
🧮 Volume calculator
| Component | Amount | Final concentration (1X) |
|---|---|---|
| 1 M sodium phosphate (pH 7.2) | 50 mL | 0.5 M |
| SDS | 7 g | 7% |
| 0.5 M EDTA (pH 8.0) | 200 µL | 1 mM |
| BSA (fraction V) | 1 g | 1% |
| Water (distilled) | to final volume |
Steps
- Warm the phosphate buffer and water and dissolve the SDS.
- Add EDTA and BSA, dissolve, and bring to volume.
- Store at room temperature and pre-warm to 65 °C before use to redissolve SDS.
Good to know
- For 1 M sodium phosphate pH 7.2, mix 1 M Na₂HPO₄ and 1 M NaH₂PO₄ roughly 2 : 1 and set with a pH meter (concentrated phosphate reads lower than dilute, so do not rely on tables alone).
- Prehybridise at 65 °C for 1 h, then hybridise overnight with probe.
FAQ
Can I use potassium phosphate?
No — potassium precipitates SDS as KDS.
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.