Simultaneous Detection of Two Analytes Using a Spectroelectrochemical Sensor

Abstract

Spectroelectrochemical sensors developed in our group achieve three modes of selectivity by combining electrochemistry, spectroscopy, and a chemically selective membrane in a single device. Analyte detection is based upon a change in the optical response due to the conversion of the analyte between two oxidation states that results from the cycling or stepping of the applied potential. We have demonstrated a novel approach to simultaneously detect two metals by combining optical stripping voltammetry for one metal (Pb(2+)) and the in situ ligand complexation in a film for the other metal (Fe(2+)). Using an indium tin oxide (ITO) sensor platform with a 50 nm Nafion film to preconcentrate the analytes, equimolar mixtures of Pb(2+) and Fe(2+) in 0.1 M sodium acetate buffer (pH 5) were detected. Pb(2+) was detected by optical stripping voltammetry, in which lead was deposited as metal on the ITO and detected by the optical change as it was removed by stripping. The ferrous ion was detected by the in situ ligand complexation method in which Fe(2+) was complexed with 2,2'-bipyridyl in the Nafion in the film to form an intense red complex that was detected by absorbance at 520 nm. Detection limits of 300 and 400 nM were obtained for Pb(2+) and Fe(2+), respectively. The presence of the film had no effect on the optical signal that results from the deposition and stripping of the Pb(2+). In addition, competition between the Pb(2+) and Fe(2+) for sites in the film and for the organic ligand was investigated.

Electrochemistry and Spectroelectrochemistry of Luminescent Europium Complexes

“…By monitoring analytes with both electrochemistry and spectroscopy, spectroelectrochemistry demonstrates a powerful capability to offer multiple levels of selectivity for a desired analyte [3,4]. The technique can isolate and identify analyte signatures by probing both select potential ranges and select wavelength ranges in either absorption or emission modes [5,6].…”

Polymer‐coated Boron Doped Diamond Optically Transparent Electrodes for Spectroelectrochemical Sensors

“…Charge selective polymers have been reported extensively throughout literature for an assortment of applications [22][23][24]. When used in spectroelectrochemistry, these polymers are coated on electrode surfaces as thin films to enhance both sensitivity and selectivity, behaving as an ion exchanger.…”

“…The charge on the film allows it to repel potential interferences of similar charge while preconcentrating analyte ions of opposite charge at the electrode surface. Our group has studied both cation and anion-exchange films and has demonstrated that extremely low detection limits can be achieved [22][23][24].…”

Impedimetric DNA‐Based Biosensor for Silver Ions Detection with Hemin/G‐Quadruplex Nanowire as Enhancer

“…It is reported that cytosine(C)-riched oligonucleotide aggregates selectively in the presence of Ag + with the formation of stable C-Ag + -C complexes [11,12]. Based on this, a number of strategies with the usage of different fluorescence [13][14][15], colorimetry [16] and electrochemistry [17,18] (EC) techniques have been designed to specific and sensitive detection of Ag + . Among these methods, EC biosensors, especially the electrochemical impedance spectroscopy (EIS) based biosensors have shown promising potentials for point-of-care diagnostics and other important applications [19].…”