SOLVENT-EXTRACTION OF AU(III) FOR PREPARATION OF A CARRIER-FREE MULTITRACER AND AN AU TRACER FROM AN AU TARGET

Separation of Au(III) and various carrier-free radionuclides by solven t extraction was investigated using an Au target irradiated by an ener getic heavy-ion beam. Percentage extraction of Au(III) and coextractio n of the radionuclides were determined with varying parameters such as kinds of solvent, molarity of HCl or pH, and Au concentration. Under the conditions where Au(III) was effectively extracted, namely extract ion with ethyl acetate or isobutyl methyl ketone from 3 mol.dm(-3) HCl carrier-free radionuclides of many elements were found to be more or less coextracted. Coextraction of radionuclides of some elements was f ound to increase with an increase in the concentration of Au(III). Thi s finding is ascribed to the formation of strong association of the co mplex of these elements with chloroauric acid. In order to avoid serio us loss of these elements by the extraction, lowering of the Au(III) c oncentration or the use of a masking agent such as sodium citrate is n ecessary. Gold(III) was shown to be effectively back extracted with a 0.1 mol.dm(-3) aqueous solution of 2-amino-2-hydroxymethyl-1,3-propane diol. Thus, a radiochemical procedure, has been established for prepar ing a carrier-free multitracer and an Au tracer with carrier form from an Au target irradiated with a heavy-ion beam. Both tracers are now u sed individually for chemical and biological experiments.