Tris(4,4′‐dimethyl‐2,2′‐bipyridine)iron(II)‐Exchanged Nafion for Arsenite Determination in Water Samples

Abstract

A low cost and easy‐to‐construct electrochemical sensor is fabricated for the determination of arsenite in water by using an Fe(dmbpy)32+‐exchanged (dmbpy=4,4′‐dimethyl‐2,2′‐bipyridine) Nafion (Nf) film. Arsenite at a glassy carbon electrode (GCE) coated with the Fe(dmbpy)32+‐exchanged Nf film is shown to be electrocatalytically oxidized at lower overpotentials than at a bare GCE, and a tentative mechanism is proposed for the electrocatalytic oxidation. This new electrochemical sensing platform (ESP) exhibits a wide linear calibration range (from 10 μM to 100 mM) with a correlation coefficient above 0.99 for the precise determination of arsenite; the ESP exhibits a detection limit of 10.0 μM for arsenite determination. Utility of the developed sensor is further assured by determining the concentration of arsenite present in standard aqueous samples and in samples from different water sources. Among the several interferences studied, high concentrations of Zn2+ (50 times higher than arsenite) can affect arsenite determination. Kinetic parameters, such as the diffusion coefficient, catalytic rate constant, and so forth, are determined by using chronocoulometry and chronoamperometry techniques.

Selective determination of isoniazid using bentonite clay modified electrodes

“…S7. Though this method is selective for the determination of IZ in presence of rifampin, this present method may not be suitable for the determination of IZ in the presence of nitrite or arsenite [8,10,11,18]. Further to validate this method, recovery analysis was done by the addition of varying amounts of standard IZ.…”

“…These results clearly indicate the improvement in the electron transfer kinetics of IZ oxidation in presence of Fe(dmbpy) 3 2+ species. This strong electrocatalysis phenomenon [8][9][10][11] can be applied for the quantitative determination of IZ. For that, cyclic voltammograms in the presence of increasing concentrations of IZ (from 10.0 µM to 100.0 mM) is analyzed using GC/Na + -bt/Fe(dmbpy) 3 2+ electrode which are shown in Fig.…”

“…Coating the surface of GC with a film of appropriate modifier which can accommodate/incorporate suitable electrocatalyst can achieve this goal. We have reported recently our work on the development of electrochemical sensors for nitrite, IZ and arsenite based on metal complexes of iron immobilized electrodes [8][9][10][11]. There is a wide range of modifiers (organic polymers and inorganic matrixes with or without ion exchange groups) which can be used for the purpose [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25].…”

Hydrophobicity effects in iron polypyridyl complex electrocatalysis within Nafion thin-film electrodes

“…Nafion coated GC electrodes (GC/Nf) (typical thickness 0.9 µm) were prepared following the procedure used in previous reports. 12,39,46,47 GC/Nf/Fe(bp)3 2+ , GC/Nf/Fe(dm)3 2+ , GC/Nf/Fe(ph)3 2+ , and GC/Nf/Fe(tm)3 2+ electrodes were prepared by dipping GC/Nf electrodes in 0.5 mM aqueous solutions of respective metal complexes for 30 min and then rinsing with triple distilled water. Metal complex ions were exchanged/immobilized onto electrodes and were then continuously potential cycled between 0.2 to 1.3 V vs. Ag/AgCl in 0.1 M Na2SO4 (scan rate 20 mVs -1 ) until a constant current was observed.…”

“…44,45 In this work, the immobilization of iron polypyridyl complexes are achieved following a previously published procedure. 12,39,46,47 Depending upon the metal complex immobilized in the Nafion (Nf) thin film electrode, the resulting electrochemical systems are represented as GC/Nf/Fe(bp)3 2+ , GC/Nf/Fe(ph)3 2+ , GC/Nf/Fe(dm)3 2+ , and GC/Nf/Fe(tm)3 2+ . Fig.…”