Would like to know the protocol for preparing tris sulfate buffer pH 7.4, searched across the web, but could not find out across a correct article, thanking you.
Titrate a solution of Tris base with a solution of sulfuric acid while stirring with a magnetic stirrer until the pH is a bit higher than 7.4. Start at a higher Tris concentration than the desired one. The temperature of the solution will increase during the titration, which will alter the pH, so allow it to cool back to room temperature before finishing the titration. Then dilute the solution with water to the desired concentration.
Take due care when working with sulfuric acid. Wear gloves, eye protection, and a lab coat. Add the acid dropwise to the Tris solution. If possible avoid using concentrated sulfuric acid - use a diluted acid solution such as 4 Molar.
The pKa of Tris is higher than 7.4, so the titration will accelerate once you drop below pH 8. Be careful not to overshoot.
You can get a good idea of how much sulfuric acid you will need if you realize that Tris has a single titratable amino group but sulfuric acid has 2 protons. To neutralize 1 mole of Tris, you need 1/2 mole of H2SO4.
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