阳离子胶束介质中次磷酸钠还原偶氮胂Ⅰ褪色催化动力学光度法测定痕量硒(Ⅳ)  

Kinetic Spectrophotometric Method for the Determination of Selenium (Ⅳ) by Its Catalytic Effect on the Reduction of Arsenazo Ⅰ with Sodium Hypophosphite in Cationic Micellar Media

作　　者：周之荣[1] 王群[2] 章淑媛[2] 

机构地区：[1]广东药学院公共卫生学院,广东广州510240 [2]东华理工大学校医院,江西抚州344000

出　　处：《食品研究与开发》2010年第5期126-130,共5页Food Research and Development

基　　金：广东省高等学校人才引进专项资金资助项目(粤材教[2009]109号);广东药学院科研基金资助项目(2007GGW03)

摘　　要：基于0.02 mol/L的H2SO4介质中存在阳离子胶束时,痕量硒（IV）对次磷酸钠还原偶氮胂I（AsA I）的褪色反应有明显的催化作用,建立了测定痕量硒（IV）的动力学光度法。在固定加热时间段（8 min）后,于500 nm处测定AsA I的吸光度减少值监控反应速率。方法检出限为0.053μg/L,线性范围为0.0~1.0μg/L。讨论了酸度、反应物浓度、表面活性剂的种类和用量、温度、反应时间、干扰离子等因数的影响。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45.69 kJ/mol。在25 mL溶液中,分别测定0.01μg、0.02μg硒（IV）的相对标准偏差为2.1%、1.9%（n=11）。结合巯基葡聚糖凝胶分离富集,方法用于测定食品和人发样品中的痕量硒（IV）,结果与ICP-AES值相符。相对标准偏差为2.7%~5.8%,加标回收率为96.0%~101.5%。A simple and sensitive kinetic spectrophotometric method for the determination of trace selenium（IV） is described.The method is based on the catalytic effect of Se（IV）on the reduction arsenazo I（AsA I）with sodium hypophosphite（NaH2PO2）in a solution of 0.02 mol/L sulfuric acid and in the presence of cationic micellar media.The reaction rate is monitored spectrophotometrically by measuring the decrease in absorbance of AsA I at 500 nm with a fixed-time method.The decrease in the absorbance of AsA I is proportional to the concentration of Se（IV）in the range 0.0-1.0 μg/L with a fixed time of 8 min from the initiation of the reaction.The detection limit of the method for Se（IV） is 0.053 μg/L.The influence of the factors such as acidity,concentration of reactants,type and concentration of surfactants,reactive time,temperature and co-existing ions on the reaction is discussed.The optimum reaction conditions of reaction are established and some kinetic parameters are determined;the apparent activation energy of catalytic reaction is 45.69 kJ/mol.The relative standard deviation for eleven replicate determination of 0.02,and 0.01 μg/25mL Se（IV） was 1.9 % and 2.1 %,respectively.Combined with sulphydryl dextrane gel（SDG） separation and enriching,the method has been successfully applied to the determination of Se（IV） in foodstuff and human hair samples with the relative standard deviation over 2.7 %-5.8 % and the recovery over 96.0 %-101.5 %,the results are in good agreement with those provided by ICP-AES method.

关 键 词：硒(IV) 动力学光度法 偶氮胂I 次磷酸钠 阳离子胶束 

分 类 号：O657.3[理学—分析化学] O613.52[理学—化学]