In the DPD titrimetric method for chlorine, what titrant is typically used?

In the DPD titrimetric method for chlorine analysis, Ferrous Ammonium Sulfate is utilized as the titrant. This method relies on the reaction between free chlorine in the sample and the DPD (N,N-diethyl-p-phenylenediamine) reagent, where the color change indicates the presence and concentration of chlorine.

When chlorine is present, it reacts with DPD to form a pink color. To quantify the amount of chlorine, Ferrous Ammonium Sulfate serves as the titrant, which reduces the chlorine, allowing the analyst to determine how much chlorine was present based on the volume of titrant used to achieve the endpoint. The importance of using Ferrous Ammonium Sulfate lies in its effective ability to react with the oxidized form of chlorine, allowing for accurate results in determining chlorine levels in water samples.

Using other agents as titrants, such as Sodium Thiosulfate, would not yield the same result because Thiosulfate is primarily used in the iodometric method, while Potassium Iodide and Phenylarsine Oxide serve entirely different functions and are not suitable for chlorine determination in a DPD-based analysis.