Abstract：A new kinetic fluorometric method for the determination of trace As was proposed based on the catalytic effect of As on the oxidation of neutral red by potassium iodate in H2SO4 medium, which lowered the fluorescence intensity. The effect of experiment conditions on the determination of arsenic was detailedly studied, including the dosages of neutral red, potassium iodate and sulfuric acid, the reaction temperature and the reaction time. The results indicated that the mass concentration of arsenic in the range of 2.0-600 μg/L was linear to the change of solution fluorescence intensity. Detection limit was 0.6 μg/L. The proposed method has been applied to the determination of arsenic in environmental water sample with relative standard deviations (RSD) less than or equal to 3.5 % and standard addition recoveries of 98%-101%.
