Acid-base status of biological fluids: Amount of acid, kind of acid, anion-cation difference, and buffer value

Abstract

A formal concept of amount of substance of ‘acid’ and ‘base’ is proposed which is based upon the change in extent of protolytic equilibria in an arbitrary reference state for the components of the system concerned and equally consistent with the Brønsted-Lowry terminology, the older medical ‘anion-cation’ terminology, and the operational principle of titration. It is shown how this concept allows formulations of the ‘acid-base status’ of biological fluids in accordance with various types of physiological, biochemical, or clinical problems. Finally, a general expression for buffer value is presented which is valid for any acid, base, or ampholyte at any pH.

Key Words:

• acid—base status
• amount of acid
• anion—cation difference
• buffer value
• kind of acid
• titratable acid