Selective Electrochemical Analysis of Various Metal Ions at an EDTA Bonded Conducting Polymer Modified Electrode

Abstract

An EDTA-bonded conducting polymer modified electrode was prepared and characterized by FT-IR. The modified electrode was used for the selective electrochemical analysis of various trace metal ions such as, Cu(II), Hg(II), Pb(II), Co(II), Ni(II), Fe(II), Cd(II), and Zn(II) at the different pHs by linear sweep and square wave voltammetry. Dynamic ranges were obtained using square wave voltammetry from 0.1 mM to 10.0 mM for Co(II), Ni(II), Cd(II), Fe(II), and Zn(II) and 0.5 nM to 20 nM for Cu(II), Hg(II), and Pb(II) after 10 min of preconcentration. The detection limits were determined to be 0. , and ion-selective electrodes (ISE) [6,7] have also been used as an indicator electrode to detect the end point in the EDTA titration. As confirmed [8] indication with a platinum electrode in the presence of a proper redox system leads to an accurate result. However, under certain conditions, formation of mercury(I) precipitates or complexes may result in incorrect end points [9]. A disadvantage of using a silver electrode in the EDTA titration is that the chloride ion should be removed from the titrant solution [10]. ISE×s have also a few disadvantages in the potentiometric titrations with EDTA. Many potentiometric ISE×s suffer from limited lifetimes as their sensing membranes may lose their ability to respond after repeated exposures to corrosive or fouling solutions. Thus, a simple analytical method for the trace analyses of various metal ions with a single electrode is necessary as a potentially alternative method to the potentiometric EDTA titration, because the potentiometric titration is not suitable for trace analysis.Stripping voltammetry is one of the most sensitive electrochemical methods for the determination of trace metals. The method is based on the preconcentration/ stripping of an analyte in the sample solution [11,12]. The stripping methods using chemically modified electrode (CME) has higher selectivity due to the ability of the modifier to capture the specific metal ion via chemical reactions [13 ± 18]. Applications of conductive polymer modified electrodes (CPMEs) to the detection of metal ions using stripping voltammetry have received considerable attention in the past and became popular [19 ± 22].The incorporation of a complexing ligand to the conducting polymer as a modifier has also been used to accumulate metal ions chemically. For example, 2,6-pyridinedicarboxylic acid (PDCA) and ethylenediaminetetraacitic acid (EDTA) simply doped in the polypyrrole film were employed for the determination of silver ions [23]. In this case, the formation of the polypyrrole/EDTA film was not reproducible due to simple doping of EDTA in the polypyrrole film.Most of the CPMEs, so far reported are restricted to use in the one or two metal ion detections. Thus, the fabrication of a new CPME, which can detect various metal ions is necessary. A single EDTA-CPME can be advantageously employed for the detection of many metal ions at different pHs.In the present work, we report the EDTA-bonded conducting polymer modi...

Electrode Materials (Bulk Materials and Modification)

“….). [520][521][522][523][524][525][526][527] Heavy metals are generally detected by pulsed voltammetry techniques with detection limits in the nM range. Molecularly imprinted polymers have been developed for the detection of small organic molecules relevant to environmental applications.…”

Chemically Modified Carbon Nanotubes: Derivatization and Their Applications

“…electropolymerization either by potential cycling or under galvonostatic conditions. Electropolymerization on rigid electrode has got considerable attention in recent years due to the possibility of having great control over the thickness of the polymer layer on the surface of CNTs [26][27][28]. In this way MWCNTs were modified with polydiphenylamine(PDPA), Poly(acrylic acid), Quinone -o -phenylenediamine, Osmium (4,4 -dimethyl -2, 2 -bipyridine) chloride and also with most popular electron-conducting polymers like polyaniline(PANI), polypyrrole (PPy) and the derivatives of polythiophene(PTh).…”

Modified carbon-containing electrodes in stripping voltammetry of metals

“…Some investigators implanted analytical reagents into the structure of current-conducting polymers [148-154, 162-163, 178] providing the enhanced selectivity of the polymer film. The high selectivity to metal ions was achieved [174][175] because polymers with covalently grafted ethylenediaminetetraacetic acid (EDTA) groups were synthesized on GCE. The response selectivity is efficiently improved by the "guest-host" interaction.…”