1. Potentiometric assays

1.1 General

Potentiometric dosing, also known as direct potentiometry, is any method for determining concentration based on the Nernst relationship between electrode potential and activity of the species in solution. Depending on the way in which the logarithmic relationship between these two quantities is exploited, several dosing methods are defined. Before describing these methods, a few general points should be made about the equipment to be used. This reminder may be superfluous if the appropriate ionometer-selective electrode pair is purchased, but it is useful in certain cases.

Like pH meters, ionometers are in fact electronic millivoltmeters that allow direct reading of the concentration X (or pX value) of the ion to be measured. The same precautions...