The HI93711-03 are high quality reagents that are pre-measured, allowing for users to achieve fast and accurate colorimetric measurements. These reagents follow the DPD Method in which the reaction between chlorine and reagent causes a pink tint in the sample. The intensity of color is determined by a compatible photometer and the total chlorine concentration will be displayed in mg/L (ppm). These reagents are designed to be used with samples that have an expected range of 0.00 to 5.00 mg/L total chlorine.