Question on Redox

Q: How to measure redox?

A: The principle is to carry out redox reaction and compare to a reference set.

From the notes: Redox measurements of pure chemicals are obtained by measuring the voltage
obtained when a mixture of oxidizing agent and its product [e.g. oxygen + water] is put into contact with a mixture of a reference pair of compounds [oxidized form + reduced form]. The reference set, by convention, is H+/H2  at pH 0. The direction of the reaction and the voltage obtained depends on which substance is the best oxidizing agent and how good it is relative to the other potential oxidizing agent in the mixture. If the oxygen/water pair is being evaluated, we will be comparing oxygen to H+. You can use the same system to measure the redox potential of a food. In this case, the food is substituted for the pair of pure chemicals to be measured, and it is measured against the standard reference set.