Spectroelectrochemical Sensor: Development and Applications

Abstract

The spectroelectrochemical sensor concept uses electrochemistry to modulate an optical signal to give improved selectivity. The sensor consists of an optically transparent electrode/waveguide coated with a thin film that preconcentrates the analyte. The sensor concept was first demonstrated with ferricyanide and later it was shown to work on a complex sample by detecting ferrocyanide in radioactive Hanford tank waste. Nafion, partially sulfonated polystyrene-block-polyethylene-ran-butylene)block-polystyrene (SSEBS), and quaternized poly(vinylpyridine) (QPVP) are examples of polymers used for the thin film. Detection limits achieved by the sensor are 10-5 to 10-8 M using change in absorbance as the mode of detection and about 10-10 M using fluorescence. A sensor has been developed for detecting [Re(dmpe)3]+ where dmpe = dimethylphosphinoethane, which serves as a nonradioactive analogue for complexes of radioactive 99Tc. Some polycyclic aromatic hydrocarbons have appropriate electrochemical and spectroscopic properties for spectroelectrochemical detection as demonstrated for 1-hydroxypyrene and its conjugate 1-hydroxypyrene-glucuronide.