The Open Electrochemistry Journal

2013, 5 : 1-7
Published online 2013 January 24. DOI: 10.2174/1876505X01305010001
Publisher ID: TOELECJ-5-1

Standards for pH Measurements of Bis-[(2-Hydroxyethyl)amino]acetic Acid (BICINE) from (278.15 to 328.15) K

Rabindra N. Roy , Lakshmi N. Roy , Blake M. Bodendorfer , Zachary M. Downs , Alexis L. Jenkins and Isaac B. Henson
Hoffman Department of Chemistry, Drury University, 900 N. Benton Ave., Springfield, Missouri 65802, USA.

ABSTRACT

The second dissociation constant, pK2, and related thermodynamic data for BICINE have been previously de-termined and reported from temperatures (278.15 to 328.15) K. For the present study, three buffer solutions without NaCl, and five with NaCl yielding an ionic strength (I = 0.16 mol·kg-1) similar to that of blood plasma were prepared. These buffer solutions have been evaluated in the temperature range of (278.15 to 328.15) K using the extended form of the De-bye-Hückel equation. The Bates-Guggenheim convention is only valid when I< 0.1 mol·kg-1. Values of the residual liquid junction potential (δEj) between the BICINE solutions and the saturated KCl calomel electrode have been estimated at (298.15 and 310.15) K. Two BICINE buffer solutions are recommended as primary standard reference solutions for pH measurements of biological fluids.

Keywords:

Buffer, Zwitterionic, BICINE.