The determination of traces of arsenic in water by arsine generation and radiometric analysis

A tracer method based on the concentration-dependent distribution principle has been developed for trace arsenic determination. Standard and sample arsenic solutions labelled with a fixed amount of radioactive arsenic-74 are isolated by arsine generation with sodium borohydride followed by absorption in potassium iodide-iodine solution. The separated arsenic(III) is then extracted with equal but limited amounts of zinc diethyl-dithiocarbamate in chloroform and determined radiometrically by the concentration-dependent distribution principle. The method is practically free from interferences, and arsenic in aqueous solution as low as 0.5 ng ml-1 can be determined. Results for natural and environmental water samples are compared with results obtained by the arsine generation-atomic absorption technique