Overoxidized Polypyrrole Doped with 4,5-Dihydroxy-3-(p-sulfophenylazo)-2,7-naphthalene Disulfonic Acid as a Selective and Regenerable Film for the Stripping Detection of Copper(II)

Abstract

Stripping voltammetry is a very sensitive method for the determination of many traces of metal ions and organic compounds. It achieves such fine levels of detection by combining an accumulation process with a voltage scanning measurement. 1,2 The universal working electrodes for stripping analysis are hanging mercury drop electrodes (HMDE) and electrochemically generated mercury film electrodes (MFE). 3 Recently, because of mercury toxic effects, there has been a growing interest in the use of chemically modified electrodes (CME) for trace metal stripping analysis. With this process, accumulation usually occurs by reactions between an analyte and an immobilized modifier at the electrode surface. [1][2][3][4][5] Electrically conducting polymers (ECPs), such as polypyrrole (PPy), can be used for the immobilization of complexing reagents for trace metal complexation/accumulation with voltammetric detection of the complexed metal.6,7 Numerous anionic ligands have been incorporated into a PPy matrix as functional dopants for the stripping analysis of metal ions. 8 The preparation of these functional PPy films is very simple, controllable and reproducible by electrochemical oxidizing pyrrole monomers in the presence of the target anionic reagents. 9 However, a major limitation lies in the high background currents typically encountered with modified PPy films. These currents mask the relatively smaller metal-chelate binding, thereby making metal detection difficult. 10One solution of this problem is to overoxidize PPy via the application of a high anodic potential in high-pH medias. [11][12][13] In the following section we present the ability of overoxidized polypyrrole (OPPy) film doped with an anionic complexing ligand, 4,5-dihydroxy-3-(p-sulfophenylazo)-2,7-naphthalene disulfonic acid (SPADNS, Fig. 1), to preconcentrate Cu(II) ions. SPADNS is an anion, and can thus be incorporated into a growing polycationic PPy film, and can also preconcentrate copper ions at an electrode surface by complexation. Experimental ChemicalsPyrrole (Fluka) was distilled under reduced pressure before use. SPADNS three sodium salt (Aldrich) was used as received. Other reagents were purchased from Merck and were of analytical grade. All aqueous solutions were prepared with double-distillated water. ApparatusElectrochemical measurements were made with a Metrohm multipurpose instrument Model 757. Working electrodes were 3 mm diameter platinum disks constructed in-house. The counter electrode was a platinum wire and the reference electrode was Ag/AgCl, both from Metrohm. A Metrohm pH meter, Model 710, was used for pH measurements. Film preparationPPy/SPADNS films were prepared potentiostatically by holding the potential at +0. Department of Chemistry, Shahid Bahonar University of Kerman, P. O. Box 76175-133, Kerman, IranA conducting polymer modified electrode based on the incorporation of 4,5-dihydroxy-3-(p-sulfophenylazo)-2,7-naphthalene disulfonic acid, SPADNS, as an anionic complexing ligand into polypyrrole film during electropolymerizati...

Stripping voltammetric determination of copper (II) on an overoxidized polypyrrole functionalized with Nitroso-R

“…It is better than some other reports. 6,12,25,[27][28][29]31 Reproducibility of this work was also very good. Accumulation time was lower compared to some last reports.…”

“…Accumulation time was lower compared to some last reports. 12,25,[27][28][29][30][31] Time spent for the preparation of the electrode was very lower than some other techniques. 12,26,30 This work also shows wider linear range compared to some other reports.…”

Properties and Customization of Sensor Materials for Biomedical Applications

“…PANi deposited on plastic substrates by means of ink-jet printing was used to detect pH changes both potentiometrically and spectrophotometrically (192), but the selectivity factor hampered their use in real-sample scenarios (192). A stripping voltammetric sensor based on an overoxidized PPy film was developed for the detection of copper in human hair (194). The device had a sensitive range from 2 to 250 ng ml À1 , and experimental results were in agreement with results obtained from atomic absorption spectroscopy.…”

A Selective Film Based on Poly(3‐octylthiophene) Doped with Dihydroxyanthraquinone Sulfonate

“…Figure 1 shows FTIR spectra of the P3OT-ARS and P3OT film made in 30 mM TBABF 4 . Characteristic infrared vibrations for P3OT can be found at wavenumbers 2922 and 2849 cm À1 due to the stretching vibration of CH 2 and the shoulder at 2955 cm À1 corresponds to À CH 3 asymmetric stretching vibration [32].…”