Buffer Standards for the Biochemical pH of the Zwitterionic Buffer <i>N</i>-Tris-(Hydroxymethyl) Methyl-2-Aminoethanesulfonic Acid (TES) from 5℃ to 55℃

Abstract

The authors have undertaken the determination of pH values for one buffer solution of TES without NaCl and nine buffer solutions with NaCl yielding an ionic strength I = 0.16 mol·kg -1 similar to that of blood. These buffer solutions have been evaluated in the temperature range of 5˚C to 55˚C using an extended version of the Debye-Hückel equation.The pH values are reported using 1) the Debye-Hückel extension of the Bates-Guggenheim convention in the temperature range 5˚C to 55˚C and 2) with and without liquid junction correction at 25˚C and 37˚C. These TES buffer solutions are recommended as secondary standard references for pH measurements in the range of pH 7.2 to 7.5 for physiological application with an ionic strength of I = 0.16 mol·kg -1 .