Effects of ionic radiological and chemical interferences on the chromatographic separation of a radionuclide standard solution

For characterizing radioactive samples there are two major considerations i n the application of a coupled liquid chromatography and on-line scintillat ion counting system: (1) radiological interferences and (2) chemical interf erences from the matrix. A study was conducted to identify which interferen ces from typical matrices found at several Department of Energy facilities affected the separation of a radioactive tracer solution by the coupled sys tem. The selection of potential interferent materials was determined throug h a review of characterization and monitoring studies of surface water, gro und water, and high level waste tank supernatant at those facilities. Incre mental mass loadings of contaminant were mixed with a standardized radioact ive tracer (Fe-55, Ni-63, Sr-90 and Pm-147) and then injected into a couple d system. The resultant chromatograms were compared to the chromatogram of the standard radionuclide solution to determine the effects of the chemical or radiological constituent. Relative to the radionuclide solution, Cs-137 was the only activation/fission product used in this study to effect a rad iological interference. For the natural uranium series, a radiological inte rference was observed for Sr-90 due to either a uranium isotope or a decay product of the series. No radiological interference was observed from Th-22 8, though it must be noted that the elution program was not capable of comp letely separating the decay series nuclides of natural uranium or thorium. For the chemical interferences, the effects are twofold since the chemical can affect the concentration of ions on the pre-concentration stage as well as the chromatographic separation. The general trend observed was that inc reasing the ionic strength of the chemical resulted in decreased retention fractions on the pre-concentration column and significant shifts in peak el ution times.