The HI38050-200 are high quality reagents that are pre-measured, allowing for users to achieve fast and accurate nitrate measurements with the chemical test kit. These reagents follow the cadmium reduction method to determine nitrate concentration as nitrate-nitrogen (NO₃^--N).

For determination of nitrate, nitrate ions in a sample are reduced to nitrite ions in the presence of cadmium. The reaction between the nitrite ions and the reagent causes an orange 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 nitrate concentration. These reagents are designed to be used with samples that have an expected nitrate range of 0 to 50 mg/L NO₃^--N in water and 0 to 60 mg/L NO₃^--N in soil.