SPE-氢化物发生原子荧光联用技术测定昆布中的无机砷含量

Determination of inorganic arsenic in kelp by SPE HG-AFS

目的建立氢化物发生原子荧光测定昆布中无机砷含量（亚砷酸盐As（III）和砷酸盐As（V））的方法。方法采用1%硝酸90℃水浴提取昆布中的无机砷,5%双氧水氧化As（III）成As（V）。以强阴离子交换固相萃取（SPE）技术消除一甲基砷酸（MMA）、二甲基砷酸（DMA）的干扰,无机砷以As（V）形式洗脱,氢化物发生原子荧光法（HG-AFS）测定无机砷。结果线性范围为0～20μg/L,线性相关系数0.999 7,加样回收试验低、中、高浓度平均回收率分别为83%、90%、92%,样品7次测定RSD为5.3%,方法检出限0.046μg·L-1。测定结果与液相色谱-电感耦合等离子体质谱法（LC-ICP-MS）结果比对满意。结论本方法操作简便,仪器配置要求低,满足分析测试要求,适用于一般实验室昆布中无机砷的测定。

Objective To establish a method for the determination of inorganic arsenic（As（III）and As（V））in kelp by hydride generation atomic fluorescence spectrum（HG-AFS）.Methods Inorganic arsenic was extracted by 90 ℃ water bath with 1% HNO3.As（III）was oxidised by 5% H2O2.Monomethylarsenic acid（MMA）、dimethylarsenic acid（DMA）were removed using strong anion exchange solid phase extraction（SPE）.The inorganic arsenic was eluated from the SPE as As（V））.Then the inorganic arsenic was detected by HG-AFS.Results The linearity of this method ranged from 0to 20μg/L and the correlation coefficient was 0.9997.The limit of detection was 0.046μg/L.The average spiked recoveries were 83%,90%,92% at low,medium and high concentrations,respectively.RSD of the repeatability was 5.6%.Conclusion This method was accurate,simple,feasible and rapid.It could be used for the determination of inorganic arsenic in kelp.