A sequential injection system for the analysis of nitrate and nitrite is described. The sample and reagents are aspirated and mixed by flow reversal while being propelled to a reaction coil or to the detector. The determination of nitrite is based on the Griess-llosvay reaction. Nitrate is previously reduced by hydrazine in alkaline medium and analyzed as nitrite. The sequencing and overlap of the stacked zones are key parameters that have been studied together with concentrations of reagents, influence of temperature and potential interfering ions. Under the final optimal conditions up to 400 mu M Of nitrite and nitrate can be analyzed, the detection limits being 0.07 ppm and 0.2 ppm respectively. The method has been tested with prepared standard samples, atmospheric aerosol filter extracts and wastewater samples.
机构:Eastern Regional Research Center, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, 600 East Mermaid Lane, Philadelphia
机构:Eastern Regional Research Center, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, 600 East Mermaid Lane, Philadelphia