This project is in the area of Analytical and Surface Chemistry and in the subfield of solute extraction. Professor Echegoyen will study the solution thermodynamics associated with the extraction of selected isotopes using naturally occurring and synthetically prepared crown ether ionophores. This research will use chemically or electrochemically prepared anion radicals or dianions of anthraquinone substituted crown ether ionophores. Extraction equilibria involving these species with selected cation isotopes from aqueous solution will be quantified using atomic absorption spectroscopy and electron paramagnetic resonance spectroscopy. The results obtained in this research would have a profound affect on isotope purification processes.