In the presence of sulphuric acid,interferences such as NO2-,HCO3-,CO32- etc. can be eliminated by the Zero cross technique.Beer's law is obeyed in the range of 0—130μg/50ml,and the limit of detection is 0.08μg·ml-1.The recovery is range of 95%—101%.The method was applied to the determination of nitrate content in the drinking water with satisfactory results.
