The HI38020-200 are high quality reagents that are pre-measured, allowing for users to achieve fast and accurate free and total chlorine measurements with the chemical test kit. These reagents follow the DPD (N,N-diethyl-p-phenylenediamine) method to determine free and total chlorine concentration. 

For determination of free and total chlorine, the appropriate DPD powder reagent is added to a sample containing chlorine. The reaction between chlorine and the reagent causes a pink colored complex to form; the greater the concentration, the deeper the color. A Checker Disc is included for an accurate, side-by-side, visual analysis to determine free and total chlorine concentration. These reagents are designed to be used with low, medium, and high range samples that have expected free and total chlorine ranges of 0.00 to 0.70 mg/L Cl2, 0.0 to 3.5 mg/L Cl2, and 0.0 to 10.0 mg/L Cl2, respectively.