oxidation-reduction indicator

Typically, the oxidation-reduction indicator Ferroin is added during this titration step as well.

The addition of litmus, other than explaining the pH type, acts as an oxidation-reduction indicator.

A redox indicator (also called an oxidation-reduction indicator) is an indicator that undergoes a definite color change at a specific electrode potential.

It is used as an oxidation-reduction indicator in cell viability assays for bacteria and mammalian cells, and for measuring aerobic respiration and exchange with the hyporheic zone in streams.