5% BSA blocking solution (in TBST) recipe
Blocking and antibody-dilution solution for cases where milk is unsuitable, such as phospho-specific antibodies.
🧮 Volume calculator
| Component | Amount | Final concentration (1X) |
|---|---|---|
| BSA (fraction V) | 2.5 g | 5% (w/v) |
| TBST | as needed | to final volume |
Steps
- Sprinkle BSA onto TBST and let it dissolve slowly (no vortexing).
- Bring to volume; use the same day or keep at 4 °C for 1–2 days.
Good to know
- Milk contains phosphoprotein (casein) and biotin, which interfere with phospho-antibodies and streptavidin detection.
- To reuse diluted primary antibody, add 0.02% sodium azide and keep at 4 °C (never with HRP secondaries).
FAQ
Which blocks better, milk or BSA?
Milk is cheaper and often gives lower background; follow the antibody datasheet first.
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.