Tris-HCl is the backbone buffer of molecular biology. A 1 M stock is diluted to working strength as needed. Because Tris pKa shifts with temperature, always set the pH at the temperature of use.
Ingredient amounts below update automatically.
Ingredients
| Component | Amount | Note |
|---|---|---|
| Tris base | 121.1 g | MW 121.14 g/mol |
| Deionised water | 800 mL | initial |
| Concentrated HCl | 60 mL | approx.; ~70 for pH 7.4, ~42 for pH 8.0 |
Method
- Dissolve the Tris base in about 80% of the final volume of deionised water.
- Cool to room temperature, then adjust to the desired pH with concentrated HCl while stirring and monitoring a calibrated meter.
- As a guide per litre: roughly 70 mL HCl for pH 7.4, ~60 mL for pH 7.6, and ~42 mL for pH 8.0.
- Make up to the final volume with deionised water.
- Dispense into aliquots and sterilise by autoclaving; store at room temperature.
Notes & safety
Tris pH falls about 0.03 units per °C as temperature rises. A buffer set to pH 8.0 at 4 °C will read lower at 25 °C, so calibrate and adjust at the temperature you will use it.
Consult the Safety Data Sheet for each reagent and follow your institution's protocols. Wear appropriate PPE.
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Equipment for this prep
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