Chlorine is the most popular and widely used of the disinfectants. The chlorination of water supplies, swimming pools and cooling tower waters are but a few of the everyday applications.
Free Chlorine (hypochlorous acid) reacts with Ammonia and certain Nitrogenous compounds to form Combined Chlorine. With Ammonia, the reaction produces chloramines which have very little disinfecting power, thus it is important to be able to determine the various fractions of Chlorine present at any one time.
DPD (NN Diethyl p Phenylene Diamine Sulphate) is the preferred reagent for the determination of Free, Combined and Total Chlorine. It is available in Tablet, Liquid and Powder form. A list of compatible instrumentation and test kits can be found below.
Total Chlorine can also be measured using a Potassium Iodide reagent. This can measure concentrations of up to 300 mg/l chlorine and is widely used in food manufacturing and industrial water treatment.