Simultaneous determination of alpha-emitting nuclides of radium through californium in large environmental and biological samples

A previous procedure for the simultaneous determination of all ..cap alpha..-emitting radionuclides from radium through californium in a single 10-g sample of soil has been modified for application to 50-g samples of soil and large samples of water, air dusts, vegetation ash, and soft tissue ash. Even with such large samples of soil, fusions with potassium fluoride and pyrosulfate have been retained to ensure complete dissolution of all refractory compounds including oxides, silicates, and carbides. The actinides from large water samples are concentrated by precipitation with ferrous hydroxide so that insoluble particulates as well as soluble forms will be collected, both of which can then be dissolved in the subsequent fusions to obtain complete recovery of the radionuclides present in whatever form. Protactinium, uranium, and neptunium are all precipitated with ferrous hydroxide to better than 99% in contrast to recoveries less than 50% that are obtained by the more common precipitation with ferric hydroxide. The actinides from all sample types are then precipitated with barium sulfate, extracted into Aliquat-336, electrodeposited, and analyzed by ..cap alpha.. spectrometry. Overall yields are generally larger than 90% with most of the radionuclides with electrodeposition contributing the largest and most variable error. Detection limits for a 10/sup 3/-min count at 28% counting efficiency are about 0.2 fCi/g for 50 g of soil, 1 fCi/g for 10 g of vegetation ash or soft tissue ash, 1 fCi/L for 10 L of water and 1 aCi/m/sup 3/ for 10/sup 4/ M/sup 3/ of air.