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基于3.2×10-4mol/LH2SO4介质中,痕量硒(Ⅳ)催化KIO4氧化中性红的褪色反应,建立了测定痕量硒(Ⅳ)的动力学光度法。在固定加热时间段(6min)后,于530nm处测定中性红的吸光度降低值监控反应速率。方法检出限为0.36μg/L,校准曲线的质量浓度线性范围为0～8.0μg/L。实验了酸度、反应物浓度、温度、反应时间、干扰离子等因素的影响。研究了反应的最佳条件,并测定了一些动力学参数,催化反应的表观活化能为81.60kJ/mol。11次重复测定0.1μg/25mL和0.2μg/25mLSe(Ⅳ)的相对标准偏差分别为2.1%和1.9%。方法用于食品和人发样品中痕量硒(Ⅳ)的测定,相对标准偏差为0.33%～3.8%,加标回收率为96.0%～103.0%。
A kinetic spectrophotometric method for the determination of trace selenium (Ⅳ) was developed based on the catalytic effect of trace selenium (Ⅳ) on the fading reaction of KIO4 oxidized neutral red in 3.2 × 10-4 mol / LH2SO4 media. The reaction rate was monitored after a fixed period of heating (6 min) at a reduction of absorbance of neutral red at 530 nm. The detection limit of the method was 0.36μg / L. The linear range of the calibration curve was 0 ~ 8.0μg / L. The effects of acidity, reactant concentration, temperature, reaction time, interference ions and so on were tested. The optimum reaction conditions were studied, and some kinetic parameters were determined. The apparent activation energy of the catalytic reaction was 81.60 kJ / mol. The relative standard deviations of 0.1 μg / 25 mL and 0.2 μg / 25 mL of Se (IV) in 11 replicates were 2.1% and 1.9%, respectively. The method was applied to the determination of trace selenium (Ⅳ) in food and human hair samples. The relative standard deviations were 0.33% ~ 3.8%, and the recoveries were 96.0% ~ 103.0%.