Tris is used to make a basic buffering solution. The pH of Tris buffers changes significantly with temperature, decreasing approximately 0.028 pH units per 1°C. Consequently, tris-buffered solutions should be adjusted to the desired pH at the temperature at which they will be used. Because the pKa of Tris is 8.08, avoid using Tris as a buffer below pH 7.2 or above pH 9.0.
To prepare a 1M stock solution of Tris-Cl:
- Dissolve 121 g Tris base in 800 ml H2O
- Adjust to desired pH with concentrated HCl. Approximately 70 ml HCl is needed to achieve a pH 7.4 solution, and 42 ml for a pH 8.0 solution
- Adjust volume to 1 liter with H2O
- Filter sterilize if necessary
- Store up to 6 months at 4°C or room temperature
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