阿左旗地方性砷中毒病区环境水中砷的化学形态中子活化分析

Determination of chemical forms of arsenic in environmental water for endemic arsenism disease area of Azuoqi by NAA

研究了无机砷、甲基胂酸 (MMA)和二甲基胂酸 (DMA)分离富集的最佳条件。使用没有经过照射的砷化合物 (单一的或混合的 )配制的模拟水样 ,用Fe(OH) 3 共沉淀和离子交换色层法与中子活化法相结合进行了分离和测定。由于无机砷能以盐基砷酸铁的形式被Fe(OH) 3 共沉淀 ,而有机胂不能 ,从而实现了两者的分离。用Dowex 5 0w× 8强酸型阳离子交换树脂分离MMA和DMA ,实际水样的加标回收率为 96.4 %及 10 3%。结果表明 :本方法简单、快捷 ,适用于环境水中砷的化学形态分析。

The areas of endemic arsenic disease in the Azuoqi belong to the drinking water type arsenism diseace area. A simple and sensitive method to identify the chemical forms of As was presented. Inorganic arsenic, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) were separated by the use of coprecipitation and cation exchange chromatography combined with neutron activation analysis. Separation of inorganic and organic arsenic (MMA and DMA) was based on coprecipitation with Fe(OH) 3, inorganic arsenic was coprecipited quantitativelly, but MMA and DMA was not coprecipited at all. Experiments showed that MMA and DMA in solution were adsorbed on cation exchange resin in pH2. MMA was eluted by 60mL of 0.5mol/L acetic acid-ammonium acetate buffer (pH4.7) and then 60mL of 3mol/L NH 3·H 2O was used to strip the DMA. The recovery of MMA and DMA was 96% and 103%, respectivery.