密闭微波消解-UV-Vis分光光度法测定铁观音茶叶中的铁含量

Determination of iron element in Tieguanyin tea leaf by airtight microwave digesting and UV-Vis spectrophotometry methods

建立了密闭微波消解-UV-Vis分光光度法测定铁观音茶叶中铁含量的方法。结果表明,10%盐酸羟胺5 mL、0.15%邻菲罗啉2 mL、1 mol/L醋酸钠2 mL的显色剂组合为邻二氮菲分光光度分析法测铁的最优显色条件,测试最优波长为510 nm。在最佳显色条件下,重复测定7次,测定结果的相对标准偏差(RSD)为1.4%,安溪产铁观音茶叶中的铁元素含量为174.58 mg/kg,5次平行测定的RSD为2.89%,低、中、高加标消解回收率为92.0%-94.6%。

An analytical method for determination of iron element in Tieguanyin tea leaf is established by using airtight microwave digesting and UV-Vis spectrophotometry methods.The results showed that the optimum color conditions were 5.0 mL 10% NH2OH · HCl,2.0 mL 0.15% phenanthroline and 2.0 mL 1mol/L NaAc for the detection of iron by spectrophotometry,besides the optimum measurement wavelength was 510 nm.The RSD of the 7 times repeated determination on the tea sample was 1.4% under the optimum color conditions.The iron content was 174.58 mg/kg in Tieguanyin tea from Anxi district.The RSD of the iron content for 5 times parallel determination was 2.89% and the recoveries of standard addition from low,middle and high were 92.0%-94.6%.