阻抑偶氮胂Ⅰ褪色反应动力学光度法测定痕量钒(Ⅴ)(英文)  

Kinetic spectrophotometric determination of vanadium(Ⅴ) based on its inhibitory effect on discoloring reaction of arsenazo Ⅰ and sodium hypophosphite

作　　者：周之荣[1] 李桂艳[1] 罗明标[1] 

机构地区：[1]东华理工学院应用化学系,江西抚州344000

出　　处：《冶金分析》2007年第4期22-28,共7页Metallurgical Analysis

基　　金：Project(0520002)supported by Natural Science Foundation of Jiangxi Province

摘　　要：基于0.02mol/LH2SO4介质中痕量钒(Ⅴ)阻抑NaH2PO2还原偶氮胂I(AsAI)的褪色反应,建立了测定痕量钒(Ⅴ)的动力学光度法。通过在固定时间段(8min)后于500nm处测定AsAI的吸光度降低值监控反应速率。方法检出限为0.052μg/L,校准曲线的浓度线性范围为0-4.0μg/L。在25mL溶液中,测定0.1μg钒(Ⅴ)的相对标准偏差为2.10%(n=11)。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。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43.90kJ/mol。结合离子交换树脂分离,实现了样品中痕量钒(Ⅴ)的测定。方法用于岩石、植物、茶叶和人发样品中钒(Ⅴ)的测定,结果与认定值相符,相对标准偏差为1.21%～3.12%。A simple and sensitive kinetic spectrophotometric method for the determination of trace vanadium （Ⅴ） based on its inhibitory effect on discoloring reaction of reduction arsenazo Ⅰ （AsA Ⅰ） with sodium hypophosphite in a solution of 0.02 mol/L sulfuric acid medium is described. The reaction rate is monitored spectrophotometrically by measuring the decrease in absorbance of AsA Ⅰ at 500 nm after a fixed time （8 min） . The calibration graph is linear in the range of 0 - 4.0 μg/L vanadium （Ⅴ） and the detection limit of the method is 0. 052 μg/L. 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 43.90 kJ/ mol. The relative standard deviation for 0.1μg/25mL of vanadium （Ⅴ） is 2.10 % （n= 11）. Combined with ion-exchange resin separation, the method has been successfully applied to the determination of trace vanadium （Ⅴ） in rock, plant, tea and human hair samples and the results are in good agreement with the certified values,with the relative standard deviations （RSD） of 1.21 % -3.12 %.

关 键 词：钒(Ⅴ) 动力学光度法 阻抑作用 偶氮胂Ⅰ次磷酸钠 

分 类 号：O657.3[理学—分析化学]