Monitoring of Hydrogen Peroxide, Nitrate and Nitrite in Rain Water

The relationship between hydrogen peroxide and nitrate and nitrite by monitoring these substances in rain water was investigated. For the determination of hydrogen peroxide, our previously reported FIA system was applied. For the determination of nitrate and nitrite, an FIA system consisting a copperized cadmium reduction column and 2,3-diaminonaphthalene (DAN) used as fluorescence substance was developed. Under the recommended conditions, it took 8 min to determine the sum of nitrate and nitrite while passing through the copperized cadmium reduction column; it took 6 min under the same condition to determine nitrite without passing through the column. The concentration of nitrate was calculated from the difference between the sum of nitrate and nitrite and nitrite. The detection limit, which was defined by a signal-to-noise ratio of 3, was calculated to be 0.1 μmol dm-3 for nitrite. Also, the relative standard deviation at 20 μmol dm-3 of nitrate was under 1.0% (n = 10). There was no interference from the major substances present in rain. The reaction scheme was based on the monitoring results.