Buffers for the Physiological pH Range: Studies of 4-(N-Morpholino)butanesulfonic Acid (MOBS) from 5 to 55 °C

• Published in: Journal of solution chemistry 2012-07, Vol.41 (6), p.1044-1053
• Main Authors: Roy, Rabindra N., Roy, Lakshmi N., Allen, Kathleen A., Mehrhoff, Casey J., Henson, Isaac B., Stegner, Jessica M., Jenkins, Alexis L., Shah, Ankita A., Rocchio, Stephen D.
• Format: Article
• Language: English
• Subjects: Buffer solutions; Chemistry; Chemistry and Materials Science; Chlorides; Condensed Matter Physics; Electric potential; EMF; Exact sciences and technology; General and physical chemistry; Geochemistry; Industrial Chemistry/Chemical Engineering; Inorganic Chemistry; Liquids; Oceanography; Physical Chemistry; Solutions; Strength
• ISSN: 0095-9782; 1572-8927
• DOI: 10.1007/s10953-012-9847-y

In this study, we report the pH values of two buffer solutions without chloride ion and eight buffer solutions with NaCl with an ionic strength I =0.16 mol⋅kg −1 . Electromotive force (emf) techniques have been used to get the cell potentials at 12 temperatures from 5 to 55 °C, including 37 °C. An extended form of the Bates-Guggenheim convention is used in the entire ionic strength range, 0.04 to 0.16 mol⋅kg −1 . The residual liquid junction potentials ( δE j ) of the buffer solutions of MOBS have been estimated from previous measurements with a flowing junction cell. These values of δE j have been used for correction in order to ascertain the operational pH values of four buffer solutions of MOBS at 25 and 37 °C. These solutions are recommended as pH standards for physiological application in the pH range 7.4 to 7.7.