Which test is used for measuring residual chlorine?

The DPD Test, or Diethyl-p-phenylenediamine test, is primarily used for measuring residual chlorine in water. This method involves adding a reagent, DPD, to a water sample containing chlorine. If chlorine is present, it reacts with the DPD to form a pink-colored compound. The intensity of the pink color produced is proportional to the concentration of residual chlorine in the water, allowing for quantitative measurement. This test is reliable and widely used across water treatment facilities to ensure chlorine levels are adequate for disinfection purposes without being excessive.

Other tests for measuring chlorine, while they may also be effective, do not achieve the same level of specificity or feasibility for routine use in many water treatment systems. The colorimeter test, while useful for various measurements, typically refers to measuring the absorbance of a solution and may not directly apply to chlorine specifically. The chlorimeter test may also refer to methods that focus on specific chlorine testing but is less commonly utilized than the DPD method. Perturbation tests, on the other hand, are not applicable for measuring residual chlorine and are more relevant in other contexts of water quality testing or system analysis. Therefore, the DPD test is favored for its accuracy and simplicity in evaluating residual chlorine concentrations in