0.1 M CaCl₂ (for competent cells) recipe
The simplest solution for chemically competent E. coli — wash and resuspend cells in ice-cold 0.1 M CaCl₂.
🧮 Volume calculator
| Component | Amount | Final concentration (1X) |
|---|---|---|
| CaCl₂·2H₂O | 7.35 g | 0.1 M |
| Water (distilled) | to final volume |
Steps
- Dissolve in about 80% of the final volume of water.
- Bring to the final volume with water.
- Autoclave (121 °C, 20 min). Keep cold at 4 °C.
Good to know
- For frozen stocks, resuspend in 0.1 M CaCl₂ + 15% glycerol and aliquot.
- Keep everything on ice and centrifuge at 4 °C.
FAQ
Is it less efficient than RbCl?
Usually 10⁵–10⁶ per µg — lower, but plenty for retransforming plasmids.
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.