Spectroelectrochemical Sensing Based on Multimode Selectivity Simultaneously Achievable in a Single Device. 2. Demonstration of Selectivity in the Presence of Direct Interferences

Abstract

Three modes of selectivity based on charge-selective partitioning, electrolysis potential, and spectral absorption wavelength were demonstrated simultaneously in a new type of spectroelectrochemical sensor. Operation and performance of the three modes of selectivity for detection of analytes in the presence of direct interferences were investigated using binary mixture systems. These binary mixtures consisted of Fe(CN)(6)(3-) and Ru(bpy)(3)(2+) and of Fe(CN)(6)(4-) and Ru(CN)(6)(4)(-) in aqueous solutions. Results on the Fe(CN)(6)(3-)/Ru(bpy)(3)(2+) binary mixture showed that an anion-exchange coating consisting of PDMDAAC-SiO(2) [where PDMDAAC is poly(dimethyldiallylammonium chloride)] and a cation-exchange coating consisting of Nafion-SiO(2) can trap and preconcentrate analytes with charge selection. At the same time, such coatings exclude interferences carrying the same type of charge as that of the exchange sites in the sensor coating. Using the Fe(CN)(6)(4-)/Ru(CN)(6)(4-) binary mixture, the Fe(CN)(6)(4-) component can be selectively detected by restricting the modulation potential cycled to a range specific to the redox-active Fe(CN)(6)(4-) component and simultaneously monitoring the optical response at the overlapping wavelength of 420 nm. It was also shown that, when the wavelength for optical monitoring was chosen as 500 nm, which is specific to the Ru(CN)(6)(4-) component, interference from the Fe(CN)(6)(4-) component for spectroelectrochemical detection of Ru(CN)(6)(4-) was significantly suppressed, even though the cyclic modulation potential encompassed the redox range for the Fe(CN)(6)(4-) component.

Selectivity in analytical chemistry (IUPAC Recommendations 2001)

“…The handling of near-infrared spectra in this way is a very good example of the approach [7]. Single sensors with different kinds of incorporated selectivities have also been described, where the multimode selectivity character of the sensor (e.g., a spectroelectrochemical detector using charge positioning, electrolysis potential, and spectral wavelength) was developed in order to minimize the interferences [8].…”

Waveguide surface plasmon resonance studies of surface reactions on gold electrodes

“…When used in this way the waveguide structure responds to changes in the imaginary part of the complex refractive index of the superstrate, in contrast to the planar waveguide surface plasmon resonance device which responds to changes in both the real and imaginary parts of the refractive index. For example, Piraud et al 21,22 have described an electrochemically regenerated chlorine sensor based on a lutetium phthalocyanine coated integrated waveguide structure, Dunphy et al 18,19 have used grating coupled step index slab waveguides to study adsorption of strongly coloured species at electrode surfaces, and Heineman et al 23,[25][26][27][28] have recently combined electrochemical modulation, selective adsorption into thin coatings, and planar waveguide optical measurements to develop highly sensitive and selective solution phase chemical sensors. In contrast a bare handful of papers describe SPR studies employing waveguide structures, despite the evident potential advantages of this approach.…”

Absorbance‐Based Spectroelectrochemical Sensor for [Re(dmpe)3]+ (dmpe=dimethylphosphinoethane)

“…The instrumental setup for ATR spectroelectrochemical measurements has been previously described in detail. [13,19,20] Briefly, light from the Xenon arc lamp source (ILC Technology, Model 302UV) was focused into a monochromator (Bausch & Lomb 0.25 m). The monochromator served to select the sensing wavelength and to reduce the intensity from the source.…”