How do I make a Tris buffer?

Tris or tris(hydroxymethyl) aminomethane is a zwitterionic buffer used extensively in a wide range of biotechnology applications including anion exchange chromatography, capillary electrochromatography (CEC), electrophoresis procedures, and evaluation of bacterial endotoxins, among others. The solution is most commonly made between pH 7.0 and pH 8.0. To prepare 1 Liter of Tris Buffer (1M, pH 7.2), you’ll need: 

• 121.14 grams Tris base (mw: 121.14g/mol)
• 1 liter Distilled Water

Weigh out exactly 121.14 gm Tris base and add to 880 ml distilled water in a suitable container. Slowly add concentrated hydrochloric acid (HCL) to adjust solution to desired pH. Take care to add HCL a little at a time. Add too much too quickly will change the pH rapidly. Once the desired pH is reached, top up the solution with distilled water till the volume is exactly 1 liter.