采用冷蒸气发生-原子吸收光谱法测定大米中痕量镉。大米样品经硝酸-高氯酸(5+1)混合酸消解后,在盐酸(5+95)溶液中加入溶于8 g·L-1氢氧化钠的25 g·L-1硼氢化钠溶液使与溶液中镉离子反应生成镉气态原子。分析中采用载气流量为0.8 L·min-1。试样溶液中加入硝酸镍和硫脲混合溶液作为增敏剂。于仪器中引入试样溶液,按选定的工作条件进行测定。镉的质量浓度在0.02~20.0 μg·L-1范围内与其峰面积呈线性关系,方法的检出限(3σ)为0.005 μg·L-1。应用此法对大米样品进行分析,测得镉的回收率在96.7%~103.7%之间。

CVG-AAS was applied to the determinations of cadmium in rice. Sample was digested with mixture of HNO3 and HClO4 (5+1). Gaseous cadmium atom was generated from HCl (5+95) solution by reacting with 25 g·L-1 NaBH4 solution (dissolved in 8 g·L-1 NaOH solution). Flow-rates of 0.8 L·min-1 for the carrier gas was taken in the analysis. Mixed solution of Ni(NO3)2 and thiourea was added to the sample solution as sensitizer. The sample solution was introduced and operated under the prescribed working condition of the instrument. Linear relationship between values of peak area and mass concentration of Cd was found in the range of 0.02-20.0 μg·L-1, with detection limits (3σ) of 0.005 μg·L-1. The proposed method was applied to the analysis of samples of rice, giving values of recovery in the range of 96.7%-103.7%.