双波长双指示剂-催化动力学光度法测定奶粉中的锌

Dual-wavelength catalytic kinetics spectrophotometric determination of zinc in milk powder

研究发现在HCl介质中，痕量锌对H2O2氧化甲基紫和亚甲基蓝褪色具有强烈的催化作用，通过测量580nm和668mn处催化反应体系和非催化反应体系吸光度的变化，建立了双波长双指示剂催化动力学光度法测定痕量锌的新方法。在最佳实验条件下，线性范围为1．5～60μg/L，线性方程为△A=0．0169pzn2＋（μg／mL）＋0．0019，r=0．9982，方法检出限为0．84μg/L。该方法可用于奶粉痕量锌的测定。

A new dual-wavelength dual-indicator catalytic kinetic spectrophotometric method for the determination of trace Zn（ Ⅱ ） was studied. This method was based on Zn2＋ catalyzing oxidation of methyl violet and methylene blue by H2 02 in HCl solution. The absorbance of the catalytic and uncatalytic systems at 580 nm and 668 nm were measured. Under the optimum conditions, the linear range of determination was 1.5 - 60μg/L. The linear regression equation wasAA = 0.0169pz.2＋ （μg/mL） ＋ 0.0019 with correlation coefficient of 0.9982, and the detection limit was 0. 84 μg/L. The method had been applied to the determination of Zn2＋ in milk powder samples with satisfactory msuits.