The automated determination of nitrate in water

An automated method for the determination of nitrate at low concentrations in water was developed. Nitrate was reduced to nitrite using an on-line cadmium reductor followed by the colorimetric determination of the nitrite according to the Shinn method. The reductor consisted of a copperised cadmium column with a small inner diameter which limits sample dispersion. Two variations of the method were evaluated, both showing good accuracy and precision. At a sampling frequency of 100/h the carry-over was better than 1%.