不同价态的无机砷在玻碳电极上具有较高的电化学氢化物发生效率,同时又存在较为明显的差异.通过选择不同的电流条件,采用电化学氢化物发生与原子吸收光谱联用技术有效地实现了无机砷的形态分析.对试验参数和干扰情况进行了研究.As(Ⅲ)和As(Ⅴ)检出限分别为0.2 μg·L-1和0.4 μg·L-1;对砷量为20 μg·L-1的条件下作了方法的精密度试验,测定结果的相对标准偏差(n=6)对As(Ⅲ)为1.9%和对As(Ⅴ)为3.1%.应用此方法分析了人发标准物质(GBW 09101),测得总砷量与证书值相符.

High rates of electrochemical hydride generation (EC-HG) of inorganic arsenic in tri-and penta-valent state were obtained at the glassy carbon cathode in the electrolytic cell.Differences in sensitivity and in slopes of calibration curves for As(Ⅲ) and As(Ⅴ) were also observed.Based on these facts and by selecting different conditions of electrolytic currents at 0.6 A and 1.2 A,EC-HG was hyphenated with AAS for the speciation analysis of inorganic arsenic.Various analytical factors,including the choice of supporting electrolyte,electrolytic current,interfering substances and etc.,were studied in detail.Under the optimized conditions,detection limits of the method for As(Ⅲ) and As(Ⅴ) were found to be 0.2 μg·L-1 and 0.4 μg·L-1 respectively.Precision of the method was tested at the concentration level of 20 μg·L-1,and values of RSD′s (n=6) obtained were 1.9% for As(Ⅲ) and 3.1% for As(Ⅴ).The present method was used in the analysis of a CRM sample of human hair (GBW 09101),the results of total arsenic determined were in consistency with the certified value.