Titration of Chlorine: Amperometric versus Potentiometric

The ability to accurately measure chlorine or other disinfectants in water is important for control of microorganisms. Whereas amperometry is specified for chlorine in Standard Methods for the Examination of Water and Wastewater , manufacturers of automatic titrators are marketing their potentiometric devices for such titrations. In this article, the electrochemical basis for amperometric and potentiometric endpoint detection is examined, and two amperometric and two potentiometric methods are compared. Both amperometric methods are shown to be superior to potentiometric endpoint detection and amenable to automatic titration. Finally, fundamentals of amperometry are discussed, and the simple circuit that was used to perform amperometric titrations using a modified automated pH/potentiometric titrator is presented.