正丁醇萃取-原子荧光光谱法间接测定茶叶中的钼

摘要

An analytical method for indirect determination of molybdenum in tea sample is established using atomic fluorescence spectrometry (AFS). Based upon the heteropoly arsenomolybdic acid, formed between As(V) and ammonium molybdate in 0. 3 mol/L of sulfuric acid and extractable perfectly by n-butyl al-cohol, measuring the arsenic in organic phase, in term of the stoichiometric relationship between arsenic and molybdenum, the concentration of molybdenum can be measured. Under the optimized condition, the results show that the linearity between the concentration of molybdenum and its fluorescence intensity is 0. 09 15. 0 μg/L, the limit of detection is 0. 09 μg/L, and the relative standard deviation is 2. 3%. The method has been applied to the determination of molybdenum in tea samples with the recoveries of 95. 2% -96. 9%. The method was validated by inductively coupled plasma atomic emis-sion spectrometry(ICP-AES), and the analytical results were in good.%建立了正丁醇萃取原子荧光光谱法间接测定茶叶中钼的方法.基于As(V)和钼酸铵在0.3 mol/L1H2 SO4介质中能形成砷钼杂多酸,且形成的杂多酸可以被有效地萃取到有机溶剂中,原子荧光光谱法直接测定有机相中的砷,间接得到钼的含量.在优化的实验条件下,钼含量在0.09～15.0 μg/L范围内呈良好的线性关系,方法的检出限是0.09 μg/L,相对标准偏差为2.3％,据此对不同茶叶样品进行分析,加标回收率为95.2％～96.9％.本方法对茶叶中Mo的检测结果与电感耦合等离子体原子发射光谱法相符合.