Abstract
The procedure is based on the coprecipitation of americium with bismuth phosphate from a urine sample after digestion with nitric acid. The bismuth phosphate is wet-ashed, dissolved in 6N HCI and the americium coprecipitated with lanthanum fluoride. The lanthanum fluoride is metathesized to the hydroxide and the precipitate dissolved in 2N nitric acid. Removal of concurrently metabolized plutonium is accomplished by liquid-liquid extraction of the nitric acid solution with 0.1M di(2-ethyl-hexyl)phosphoric acid (D2EHPA) in chloroform. The purified americium is carried on lanthanum fluoride. The precipitate is slurried onto a stainless steel planchet and counted in a low-background proportional alpha counter. The method is effective for quantitative separation from plutonium and uranium. Quantities of the order of 0.5 dpm of americium can be detected in a urine sample.