The HI782-25 are high-quality reagents that are pre-measured, allowing for users to achieve fast and accurate measurements with their Marine Nitrate High Range Checker^® HC. These reagents follow the Zinc reduction method in which the reaction between nitrate and the reagent causes a pink tint in the sample. By simply adding the packet of HI782-25 reagent to the sample, the reaction will take place and the HI782 will determine the concentration from the color that is produced. The results will be displayed in ppm of nitrate (as NO3–). These reagents are designed to be used with saltwater samples that have an expected range of 0.0 to 75.0 ppm.