根据As(Ⅲ)和As(Ⅴ)在HG-AFS仪器上的响应差别,利用As(Ⅲ)、As(Ⅴ)标准回归方程建立的分析因子,通过测定溶液中预还原前的荧光强度和预还原后的砷量,建立了一种高灵敏度、干扰少、快速、操作简便的HG-AFS法直接测定As(Ⅲ)和As(Ⅴ)的分析方法.对影响分析因子的各种仪器条件和共存离子干扰进行了试验,考察了样品中不同浓度As(Ⅲ)和As(Ⅴ)的测定精密度.方法的检出限As(Ⅲ)为0.050ng.ml-1,As(Ⅴ)为0.087ng.ml-1,相对误差为0.31%—19.2%,相对标准偏差为1.18%—20.96%.方法对水中As(Ⅲ)和As(Ⅴ)的测定相对标准偏差为7.55%—24.97%,回收率为89.5%—110.2%,对土壤中酸提取和磷酸盐交换性As(Ⅲ)和As(Ⅴ)的回收率为91.2%—104.8%.
A high sensitivity,low-interference,rapid and convenient method was established for the determination of As(Ⅲ)and As(Ⅴ)with hydride generation atomic fluorescence spectrometry,which was based on the difference in intensity between As(Ⅲ)and As(Ⅴ)in HG-AFS,the analytical factor from the standard curve equation of As(Ⅲ)and As(Ⅴ),and direct determination of the corresponding fluorescence intensity before and after reduction with sulfourea.The instrument conditions and interference with coexisting ions were tested,and the precision of different concentrations of As(Ⅲ)and As(Ⅴ)in the sample were also investigated.The detection limit of the method was As(Ⅲ)0.050 ng·ml-1,As(Ⅴ)0.087 ng·ml-1.The relative error was 0.31%—19.2%,the relative standard deviation was 1.18%—20.96%.The relative standard deviation was 7.55%—24.97% and the recovery was 89.5%—110.2% for the determination of As(Ⅲ)and As(Ⅴ)in water.The recovery was 91.2%—104.8% for the determination of As(Ⅲ)and As(Ⅴ)in soil extracted by acid or exchanged by phosphate.