Which kit is used for determining disinfectant/chlorine residual?

• A. DPD Kit.
• B. pH pen.
• C. Whirl-Pak bag.
• D. Bacon Bomb.

Answer: (A)

Determining disinfectant/chlorine residual is done with a colorimetric method that uses a DPD reagent. When the DPD reagent is added to a water sample containing chlorine, a pink color forms; the intensity of that pink matches how much chlorine is present, usually read against a color chart or with a small meter to give the chlorine concentration in mg/L (ppm). This kit is built specifically for detecting residual disinfectant because the color change is directly tied to chlorine levels, and with the right steps you can differentiate free chlorine from total chlorine. In contrast, a pH pen measures acidity or basicity, not chlorine residual; a Whirl-Pak bag is simply a sample container; and a Bacon Bomb isn’t a recognized test kit for water analysis.