Study on the Kinetic Spectrophotometric Determination of Selenium (IV) on Oxidation of Neutral Red with Potassium Periodate and Its Application

摘要

Based on the oxidation of neutral red by KIO_4 in 3.2×10~(-4) mol/L sulfuric acid solution, a simple kinetic spectrophotometric method was developed for the determination of trace amounts of Se(IV). The reaction was monitored spectrophotometrically by measuring the decrease in the absorbance of neutral red at 530 nm with a fixed-time method. The decrease in the absorbance of neutral red is proportional to the concentration of Se(IV) in the range 0.0-8.0 μg/L with a fixed time of 4-6 min from the initiation of the reaction. The limit of detection is 0.36 μg/L Se(IV). The influence of the factors such as acidity, concentration of reactants, reaction time, temperature and co-existing ions on the reaction is discussed. The optimum conditions of reaction are established and some kinetic parameters are determined. The apparent activation energy of catalytic reaction is 81.60 kJ/mol. The relative standard deviation for the determination of 0.1 and 0.2 μg/mL Se(IV) was 2.1 and 1.9%, respectively. The method has been successfully applied to the determination of Se (IV) in tea and human hair samples with the relative standard deviation of 0.33%-1.5% and the recovery of 97.5%-103.5%.