样品经硝酸和过氧化氢微波消解,采用在线标准加入-石墨炉原子吸收光谱法测定其中痕量铬和镉的含量.在优化的试验条件下,用磷酸(1+99)溶液作为基体改进剂测定铬,以250 g·L-1硝酸铵溶液为基体改进剂测定镉.应用所提出的方法测定了食盐中镉和大米标准物质(GBW 10010)中铬,镉的加标回收率为90.4%,相对标准偏差(n=5)均小于5.0%.

A new method for the determination of traces of Cr and Cd in food by GFAAS with on-line standard addition system was proposed in this paper.The sample was dissolved by microwave assisted digestion with a mixture of HNO3 and H2O2.Under the optimum expermental conditions,H3PO4(1+99) solution and 250 g·L-1 NH4NO3 solution were used as matrix modifiers in the determination of Cr and Cd,respectively.The proposed method was used to the determination of Cd in table salt and Cr in rice standard sample (GBW 10010),giving values of RSD (n=5) of Cr and Cd less than 5.0%.Value of recovery of Cd found by standard addition method were 90.4%.