催化动力学褪色光度法测定痕量铜（Ⅱ）的研究

研究了在盐酸介质中 ,铜 (Ⅱ )催化过氧化氢氧化孔雀绿褪色反应的适宜条件与影响因素 ,建立了催化动力学光度法测定痕量铜的新方法。该方法是用固定时间法在 6 15nm波长处监测催化反应。方法的线性范围为 0～ 2 2 μg·L- 1 ,检出限为 1 92× 10 - 9g·mL- 1 ,该催化反应对铜 (Ⅱ )为一级反应 ,表观活化能为12 2 3kJ·mol- 1 ,表观反应速率常数为 7 70× 10 - 4s- 1 。因为Fe3 干扰Cu(Ⅱ )的测定 ,用PO3-4与Fe3 生成稳定的 Fe(PO4 ) 2 ]3- 络合物 ,可掩蔽Fe3 。方法相对标准偏差为 1 16 % ,标准加入回收率为 98 3%～10 0 3%。该方法用于水样品、茶叶样品、奶粉样品以及苹果样品中铜的测定 ,获满意结果

Study on determination of trace copper(II) by catalytic kinetic discoloring spectrophotometry]

A kinetic spectrophotometric method for the determination of trace Cu(II) was developed in this paper. This method is based on the discoloring oxidation reaction between malachite green and hydrogen peroxide catalyzed by copper(II) in the medium of HCl solution. The influential factors of reaction and the optimum conditions for the determination of Cu2+ were investigated in detail. The decrease in absorbance was measured at 615 nm at fixed time intervals. The linear determination range is between 0 and 22 microg x L(-1) of copper(II). A detection limit of 1.92 microg x L(-1) is achieved. The catalytic and non-catalytic reactions are the first-order on copper(II), in the reaction time interval 15-20 min at 70 degrees C. The apparent activation energy of the catalytic reaction is 122.3 kJ x mol(-1). The apparent rate is 7.70 x 10(-4) s(-1). The Relative Standard Deviations (RSD) are 1.16% and the recoveries are 98.3%-100.3%. By masking Fe(III) ion with PO4(3-), the method can be applied to the determination of copper in water sample and foodstuffs with satisfactory results.