催化褪色光度法测定乳粉中微量锌

在硫酸介质中,锌对过氧化氢氧化甲基橙的反应体系具有催化作用,且甲基橙被氧化后的褪色程度4SΔA与锌的含量有线性关系,据此建立了甲基橙褪色光度法测定微量锌的新方法。本法最大吸收波长为5 0 6nm ,表观摩尔吸光系数为1 2×10 4L/mol·cm ,锌的浓度在0～5 2 μg/mL范围内符合比尔定律,检出限为0 12μg/mL ,回收率在92 3%～10 1 5 %之间,相对标准偏差为1 2 %～3 3%。测定结果与标准方法无显著性差异。

Determination of Trace Zinc by Catalysis Discoloration Spectrophotometry

Zinc has catalysis ability in the system of H_2O_2 oxidize methyl orange in H_2SO_4 medium, and the discoloration extent of methyl orange has a linearity to the content of zinc. Based on this fact, a new photometric method for the determination of zinc was proposed. The absorptive maximum is 506 nm,with an apparent molar absorption of 1.2×10 4 L/(mol·cm). Beer's law was obeyed in the concentration range from 0 to 5.2 μg/mL. The detection limit of this method was 0.12 μg/mL, the recovery was between 92.3%～101.5%,the relative standard deviation was 1.2%～3.3%.