For determination of nitrite, the chromotropic acid reagent reacts with the nitrite present in the sample causing an orange colored complex to form; the greater the concentration, the deeper the color. A color comparator cube is included for an accurate, side-by-side, visual analysis to determine nitrite concentration. These reagents are designed to be used with samples that have an expected nitrite range of 0.0 to 1.0 mg/L (ppm) NO₂^--N.