Apr 20th, 1:00 PM - 4:00 PM
Ion-selective Electrode for the Voltametric Determination of Trace, Aqueous Uranium Concentrations
Dr. Dale Russell
Current analytical techniques for the determination of uranium groundwater concentration require laboratory based methods or large, bulky, high voltage equipment. A lightweight, inexpensive, rapid response method is desirable for applications that would include deployment in remote, hazardous, or inaccessible regions, and could include clandestine measurement. Described is a sensor that can be incorporated into a hand-held device with a subppb detection limit and a four orders of magnitude dynamic range. The uranium selective macro-ligand, 4-sulfonic calixarene, has been incorporated into a semi-conducting, poly(thiophene) film that has been electrochemically deposited on a conductive substrate. Voltammetric response was observed to be linearly proportional to the logarithm of the uranium concentration, and an increase in sensitivity for uranium was observed in the modified electrode compared to the unmodified platinum electrode. Furthermore, response to chemical interferences such as potassium ferricyanide and thorium(IV) was markedly decreased, while sensitivity remained consistent over a wide range of pHs. The detection limit was determined to be 0.1 ppb (3σ) with a linear dynamic range of 0.1-2000 ppb.