Phosphoric Acid with Tris Buffer – pH 2.14

Preparation of 50 mL of buffer pH 2.14 (stock solution)
(0.3 M H₃PO₄, 0.19 M Tris)

H3PO4	0.300M	1 mL of 15M
Tris	0.19M	1.14 g

Dissolve 1.14 g of Tris (mol wt. 121 g/mol) in 40 mL of DI water. Using every precaution, in a fume hood add 1 mL of 15 M H₃PO₄ slowly and stir gently. Adjust pH if necessary with either 1 M Tris or 1M H3PO4. Make up volume to 50 ml (in volumetric flask) with DI water. Keep refrigerated. Dilute (1:10) before use.