Chromatographic separation of isobaric and polyatomic interferences in radionuclear ICP/MS applications

Ion chromatographic separation, combined with inductively coupled plasma mass spectroscopy detection, is proving to be a powerful and sensitive tool for inorganic and isotopic characterization of nuclear wastes from DOE defense production sites. This laboratory has developed several group separation schemes using high pressure ion chromatography (HPIC) for separating and analyzing such samples. Compared to natural samples, nuclear samples pose non-traditional ICP/MS interference problems due to altered isotopic abundances and radionuclide-derived isobaric interferences. Illustrative problems solved with the HPIC-ICP/MS approach include the separation of rare earths and actinides in spent UO{sub 2} fuel. A gradient separation using oxalic/diglycolic acid with a cation/anion column removes light rare-earth oxide interferences on heavier rare earth elements, while also enabling the determination of their non-natural isotopic abundances. Another procedure for separating and detecting 5th-row transition elements from an actual tank waste sample will be discussed. This procedure, using an HCl gradient, separates and removes isobaric and polyatomic interferences in the determination of {sup 99}Tc (from {sup 99}Ru), {sub 107}Pd (from {sub 107}Ag), and {sup 90}Sr (from {sup 90}Y and {sup 90}Zr). Finally, a procedure for the determination of {sup 129}I in simulated tank wastes using an anion column in-line with an anion membrane suppressormore » will be illustrated. This procedure allows the determination of iodine in the presence of dissolved {sup 129}Xe and in high salt solutions without diluting the sample matrix.« less