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Description
Colorimetric determination of free and total chlorine
At a pH value of 5 – 6 free chlorine reacts with N,N-diethyl-1,4-phenylene diamine (DPD) to form a red-violet dye. In the presence of iodide ions the content of total chlorine can be determined, too.
One distinguishes between free chlorine and bound chlorine (chloroamines); the sum of both is called total chlorine.
The determination of free chlorine includes the concentrations of bromine, bromoamine, chloroamine, iodine and in part chlorine dioxide.
