This kit measures nitrite to less than 0.1 mg/L and nitrate to less than 0.2 mg/L in marine or freshwater. MultiTest Nitrite. Nitrate performs over 75 tests and contains a reference sample for validation. Range: NO2 : 0-25 mg/L, NO3 : 0–50 mg/L. Precision: NO2/NO3 : 0.1–1 mg/L