The general principle employed by the FIA methodology is thereduction of nitrate to nitrite using a copperised cadmium
(Cu-Cd) reduction column. The resultant stream of nitrite which is stabilized by a buffer at a pH of 8.5 is colorimetrically determined with Griess reagent (mixture of SA and NED). This furnishes the total nitrate and nitrite content of the sample. To quantify only nitrite, the sample is not allowed to pass through the Cu-Cd reduction column. Thus the exclusion of the nitrite values from the total resulted in superlative nitrate quantification in a sample. The quantification parameters and the figure of merits of the analytical method are listed in Table 2.