Indirect spectrophotometric determination of arsenic(III) based on solid-phase extraction

建立了间接分光光度法测定砷的新方法。该方法的基础是从pH为1.5的溶液中提取砷（III），并将其作为与吡啶二硫代氨基甲酸铵（APDC）配合物的阴离子交换树脂，在膜过滤器上分离固定as (III)-APDC配合物的树脂，将树脂在含铜（II）的溶液中再分散，将无色的as (III)-APDC配合物转化为黄色的Cu(II)-APDC配合物。在膜过滤器上收集树脂，用分光光度计或密度计测量所得Cu(II)-APDC复合物在树脂相中的吸光度。二乙基二硫代氨基甲酸酯（DDTC）和EDTA的联合使用成功地抑制了干扰离子的影响。该方法应用于一个标准的河流水样。对40ml样品中砷（III，V）进行了ppb水平的测定，取得了较好的结果。

A new method for the indirect spectrophotometic determination of arsenic was developed. This method is based on the extraction of arsenic(III) from a solution of pH 1.5 on a finely divided anion-exchange resin as a complex with ammonium pyrrolidinedithiocarbamate(APDC), separation of the resin fixing the As(III)-APDC complex from the bulk solution on a membrane filter, re-dispersion of the resin in a solution containing copper(II) and conversion a coloreless As(III)-APDC complex to a yellow Cu(II)-APDC complex, collection of the rsin on a membrane filter and measurement of the absorbance of the resulting Cu(II)-APDC complex in the resin phase by a spectrophotometer or a densitometer. The effects of interfering ions were successfully suppressed with the combined use of diethyldithiocarbamate(DDTC) and EDTA. The method was applied to a standard river water sample. Good results were obtained for the detemination of arsenic(III,V) at the ppb level in 40ml of the sample.