胶束介质中催化光度法测定茶叶中痕量钴  

Catalytic Spectrophotometric Determination of Trace Cobalt(Ⅱ)in Tea

作　　者：高烨[1] 王晓菊[1] 

机构地区：[1]长春师范大学化学学院,吉林长春130032

出　　处：《食品研究与开发》2013年第17期77-79,共3页Food Research and Development

基　　金：吉林省教育厅项目(吉教科合字[2010]第382号);长春师范学院自然科学基金(长师院自科合字[2010]第023号)

摘　　要：在NH3·H2O-NH4F和十二烷基苯磺酸钠胶束介质存在下,钴对过氧化氢氧化亚甲基蓝的反应具有增强作用,据此建立了一种催化动力学光度法测定痕量钴(Ⅱ)的新方法。研究了吸收光谱、试剂用量、干扰离子等因素的影响。在最佳实验条件下,非催化反应与催化反应体系在660 nm处的吸光度差值与钴(Ⅱ)的浓度在4μg/L^240μg/L范围呈良好线性关系,检出限为2.55×10-6g/L。催化反应为动力学零级反应,表观活化能为108.14 kJ/mol,反应速率常数为0.021 mol/L·min。在十二烷基苯磺酸钠介质存在下,反应的灵敏度提高2倍。此法用于茶叶样品中钴(Ⅱ)的测定,相对标准偏差小于2.78%,试样加标回收率为97.0%~102.0%。In the medium of sulfuric acid and dodecyl benzene sulfonic acid sodium micelle, trace Cobalt （ lI ） has the catalytic effect on the reaction between methylene blue and hydrogen peroxide. Therefore,a new catalytic kinetic spectrophotometric method for the determination of the trace Cobalt （ I1 ） was established. The effect of these factors of absorption spectra, acidity, concentration of reagent and influence of coexisting ions on the reaction was discussed. Under the optimum conditions, good linear relationship was obtained between absorbance differece （AA） of the non-catalytic system and catalytic system at 660 nm and the concentration of Cobalt （ 11 ）in the range of 4 μg/L-240 μg/L, the detection limit is 2.55x10μ g/L. The catalytic reaction was the zero-order reaction and and apparent activation energy of the catalytic reaction 108.14 kJ/mol, and the reaction rate constant was corresponding to 0.021 mol/L＇min. The sensitivity is increased by 2 times than in the absence of dodecyl benzene sulfonic acid sodium micelle. The method can be used for the determination of cobalt （ 11 ）in tea samples with the relative standard deviation of below 2.78 % and the average recovery of 97.0 %-102.0 %.

关 键 词：十二烷基苯磺酸钠 胶束介质 催化动力学光度法 钴(Ⅱ) 过氧化氢 亚甲基蓝 

分 类 号：O657.3[理学—分析化学] TS272.7[理学—化学]