Spectroelectrochemical Sensing Based on Multimode Selectivity Simultaneously Achievable in a Single Device. 21. Selective Chemical Sensing Using Sulfonated Polystyrene-block-poly(ethylene-ran-butylene)block-polystyrene Thin Films

Abstract

Spectroelectrochemical sensors combine three modes of selectivity in a single device (electrochemistry, spectroscopy, and selective partitioning). A thin polymer film is coated onto the sensing platform in order to facilitate chemically selective transport to the electrode. The film is an essential part of the sensor because it provides an increase in selectivity and sensitivity by selectively preconcentrating the analyte. Here, we report the next step in the characterization of partially sulfonated polystyrene-block-poly(ethylene-ran-butylene)block-polystyrene (SSEBS) films for the purpose of chemical sensing by examining the selectivity of the sensor fabricated with this novel thin film material. Binary mixtures using model analytes were used to demonstrate the sensor's ability to detect an analyte in the presence of a direct interference. The binary mixtures consisted of Ru(bpy)(3)(2+)/Fe(CN)(6)(3-), Ru(bpy)(3)(2+)/Fe(bpy)(3)(2+), and Ru(bpy)(3)(2+)/Cu(bpy)(2)(2+). Demonstration of the selective partitioning mode using the Ru(bpy)(3)(2+)/Fe(CN)(6)(3-) mixture and absorption detection showed the SSEBS film's preference for Ru(bpy)(3)(2+) over Fe(CN)(6)(3-), and therefore, Fe(CN)(6)(3-) did not interfere with the sensor's response to Ru(bpy)(3)(2+). Furthermore, the importance of the use of three modes together was demonstrated by analysis of the Ru(bpy)(3)(2+)/Fe(bpy)(3)(2+) and the Ru(bpy)(3)(2+)/Cu(bpy)(2)(2+) test mixtures, where both selection of a specific wavelength for absorption and selection of a specific potential window were required to reduce or eliminate the signal from the interference. Finally, analysis of the Ru(bpy)(3)(2+)/Fe(bpy)(3)(2+) test mixture was also demonstrated using fluorescence detection.

Bare and Polymer-Coated Indium Tin Oxide as Working Electrodes for Manganese Cathodic Stripping Voltammetry

“…32,35 It has been reported in literature that SSEBS is capable of uptaking positively charged analytes while repelling negatively charged interferences. 32,35 ITO has been used for spectroelectrochemical stripping voltammetry where an optical change associated with the stripping of preconcentrated metal is used as the analytical signal. 37–39 However, neither bare ITO nor SSEBS coated ITO have ever been used as an electrode material for CSV of Mn 2+ .…”

“…ITO can also be used in acidic buffers, which proved to be important for this work. Because of the experience in our laboratory with polymer films that pre-concentrate charged analytes by ion exchange and provide selectivity, we also investigated the effect of charged polymer films on the CSV of Mn 2+ 30,35 . We compared SSEBS and Nafion, polymers that we have used previously to preconcentrate cationic analytes such as Ru(bipy) 3 2+ , Cu(bipy) 2 2+ , and Fe(bipy) 3 2+ on ITO for spectroelectrochemical sensing.…”

Spectroelectrochemical Sensing: Current Trends and Challenges

“…ATR has been widely used to determine different analytes , and the combination with sensing films is an interesting strategy for analytical purposes. For example, a SEC sensor can be developed for a metal ion that lacks the optical properties needed for this type of sensors by forming a strongly absorbing metal complex within a sensing film.…”

Non-pertechnetate Technetium Sensor Research and Development

“…The electrochemical components included 1a Princeton Applied Research 237A (EG&G) potentiostat with Corrware software v3.3b from Scribner Associates. (Andria et al 2009;Kaval et al 2003) Technetium-99 NMR spectroscopy. The NMR sample solutions were placed in capped polytetrafluoroethylene (PTFE)/fluorinated ethylene propylene (FEO) copolymer sleeves (Wilmad), which were inserted into 5-or 10-mm glass NMR tubes to provide secondary containment for the radioactive liquid.…”