KBrO_3氧化甲基紫褪色动力学光度法测定食品中痕量钒

Kinetic spectrophotometric determination of trace vanadium in foodstuff based on oxidation discoloration of methyl violet with potassium bromate

基于0.004 mol/L的柠檬酸介质中,痕量V(Ⅴ)催化KBrO3氧化甲基紫的褪色反应,建立了测定痕量V(Ⅴ)的动力学光度法。方法的检出限为1.23μg/L,线性范围为0～0.16μg/mL。讨论了酸度、反应物浓度、温度、反应时间、干扰离子等因素的影响,确定了该体系反应的最佳条件。在25 mL溶液中,测定2.0μg V(Ⅴ)的RSD为1.9%(n=11)。方法可用于测定小麦和苹果中的痕量V(Ⅴ),RSD为1.1%～2.7%,标准加入回收率为97.6%～99.0%。

Based on the catalytic effect of trace amount vanadium（Ⅴ） on oxidation of methyl violet by potassium bromate in 0.004 mol/L citric acid solution,a new kinetic spectrophotometric method for the determination of trace amount vanadium（Ⅴ） has been developed.The detection limit is 1.23 μg/L and the linear range of determination is 0.0-0.16 μg/mL for vanadium（Ⅴ）.The relative standard deviation for the determination of vanadium（Ⅴ） at the concentration of 2.0 μg/25 mL is calculated to be 1.9%（n = 11）.The factors such as acidity,concentrations of reactants,reactive time,temperature,influence of coexisting ions on the reaction and the optimum reaction conditions of the reaction were determined.The method has been applied to the determination of trace amount vanadium（Ⅴ） in wheat and apple samples with the relative standard deviations of 1.1% ～ 2.7% and the recoveries of 97.6% ～ 99.0%.