Acid-base and oxidation-reduction relationships

pH, the symbol for "hydrogen-ion concentration", is a series of dimensionless "units" that have only general significance. The author shows that, when considered on the basis of the relationship to oxidation-reduction, the relative significance of any pair of coordinates becomes more significant. However, the theoretical relationship as currently accepted by the Nernst equation, i.e. a shift of 59.1 milivolts for each shift of 1.0 pH, does not apply to macromolecular systems, such as in vivo. The author solved this difficulty by plotting the corrdinates graphically by bisecting pH relationships at 7.0 and oxidation-reduction relationships at Eh 0.0 milivolts, forming four quadrants. With this scheme the significance of any pair of coordinates can be readily recognized. The application of this method to biology and medicine is shown in the companion paper "pH and Eh relationships in the body".