The HI93713-01 are high quality reagents that are pre-measured, allowing for users to achieve fast and accurate colorimetric measurements. The method is an adaptation of the ascorbic acid method in which the reaction between phosphate and the reagent causes a blue tint in the sample. The intensity of color is determined by a compatible photometer and the phosphate 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 2.50 mg/L (ppm) phosphate.