Improvement of the UV-induced Reduction Efficiency of Nitrate by Manganese (II) chloride based on Sequential Injection Analysis

Abstract

Abstract The traditional method of reducing nitrate by ultraviolet radiation was improved in this study. Manganous (II) Chloride (MnCl2) was added on the basis of original reagent to improve the efficiency of nitrate reduction by Ultraviolet radiation (UV), and the optimum reaction conditions of improved UV reduction method were discussed. It was found that the best UV-reduced reduction efficiency of nitrate obtained at the concentration of 1.0 g/L photoreduction DTPA, the concentration of Tris was 1.0 g/L with 8.0 of pH in the presence of 0.8g/L MnCl2 with 2 min UV radiation. The reduction efficiency increased by about 25.00% compared with the traditional analysis method, reached to 88.24%. The linear relationship of the established method was good at the range of 0-500μg/L, and the detection limit was 2.17μg/L. The average concentration of nitrate in the coastal seawater was 8.89μg/L and the relative standard deviation was 0.23%. We added the standard solution of NO3-N with the concentrations of 100μg/L and 300μg/L to the seawater samples, respectively, with the recovery of standard addition among 99.90%~100.34%. The established method improved the UV reduction efficiency of nitrate and got high reproducibility and good accuracy which can be used to monitor nitrate content by in-situ analyzer.