ICP-AES Determination of Trace Elements in Tea-leaves with Microwave Assisted Sample Digestion

Samples of tea-leaves were digested by microwave assisted digestion,and trace amounts of Cu,Zn,Fe,Mn,Pb and Ba in sample solutions were determined by ICP-AES. Influtential factors of digestion process,including the volume ratio of HNO3 and HClO4,the liquid to soild ratio of the system,particle size of sample,and digestion time were studied by the orthogonal experimental designing method. Under the optimum conditions,values of RSD′s (n=7) of Cu,Zn,Fe,Mn,Pb,Ba found were in the range of 0.68%-1.98%,and values of recovery found were in the range of 97.0%-102.3%. Detection limits (3S/N) of 6 elements were less than 0.030 μg·L-1. The proposed method was used in the analysis a CRM of tea-leaves (GBW 08513),the results obtained were in conformity with the certified values.