Electroanalysis of the Herbicide Diquat by Electrochemical Detector Containing Particles of Clay in Environmental Water (original) (raw)
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Materials Chemistry and Physics, 2008
The electrochemical behavior of diquat at carbon paste electrode modified by fluoroapatite (FAP-CPE) was studied in 0.1 M K 2 SO 4 using cyclic and square wave voltammetry. The diquat herbicide presented two reduction peaks, in −0.69 and −0.97 V, with profile of the totally reversible redox process. The influence of various experimental parameters on the FAP-CPE response was investigated (i.e. pH of electrolyte, carbon paste composition, accumulation time). The two reduction peaks showed that the peaks currents were found to be directly proportional to the herbicide concentration with detection limits (DL, 3σ) of 3.1 × 10 −8 and 7.6 × 10 −7 mol L −1 for peaks 1 and 2 respectively. In addition, the proposed methodology was applied in the river water samples, contaminated by diquat, without any pre-treatment step. Results indicated that the methodology could be employed to analyze diquat in such matrices.
Talanta, 2009
This paper describes the use of a dental amalgam electrode (DAE) to evaluate the electrochemical behaviour and to develop an electroanalytical procedure for determination of diquat herbicide in natural water and potato samples. The work was based on the square wave voltammetry responses of diquat, which presented two well-defined and reversible reduction peaks, at −0.56 V (peak 1) and −1.00 V (peak 2). The experimental and voltammetric parameters were optimised, and the analytical curves were constructed and compared to similar curves performed by high performance liquid chromatography coupled to ultraviolet-visible spectrophotometric detector (HPLC/UV-vis). The responses were directly proportional to diquat concentration in a large interval of concentration, and the calculated detection limits were very similar, around 10 g L −1 (10 ppb) for voltammetric and chromatographic experiments. These values were lower than the maximum residue limit established for natural water by the Brazilian Environmental Agency. The recovery percentages in pure electrolyte, natural water and potato samples showed values from 70% to 130%, demonstrating that the voltammetric methodology proposed is suitable for determining any contamination by diquat in different samples, minimising the toxic residues due to the use of liquid mercury or the adsorptive process relative to use of other solid surfaces.
Studies on Degradation of Diquat Pesticide in Aqueous Solutions Using Electrochemical Method
The C/PbO 2 electrode assisted electrochemical removal of diquat dibromide herbicides solutions has been the subject of the present investigation under several operating conditions. The optimum conditions of the treatment process are: current density of 150 mA/cm 2 , pH 2.2, NaCl concentration 2 g/L, temperature of 10˚C and initial diquat concentration of 50 mg/L. The time of electrolysis is 60 min for degradation rate of diquat and chemical oxygen demand (COD) removal is 210 min. The results were obtained by UV-Vis spectrophotometer and the present designed electrode was coincident.
Analytical Letters, 2005
O uso da voltametria de onda quadrada para a determinação eletroanalítica do picloram em meio aquoso é discutido neste trabalho. Encontrou-se que a reação ocorre por um mecanismo irreversível, envolvendo a transferência de quatro elétrons, com o reagente adsorvido na superfície do eletrodo. Uma aplicação prática foi levada a efeito, com amostras de águas contaminadas artificialmente com o herbicida. Estas amostras consistiam de água pura e de três diferentes amostras, coletadas em três diferentes riachos da região, dois dos quais eram altamente poluídos com efluentes domésticos e industriais. Os limites de detecção calculados variaram entre 11 (para a água pura) e 39 ppb para a amostra mais contaminada. Estes valores são suficientemente baixos para indicar a metodologia em aplicações de análise de traços. This paper describes the use of square wave voltammetry for the electroanalytical determination of picloram in aqueous media. The reaction was found to occur via an irreversible mechanism involving the transference of four electrons, with the reagent adsorbed in the electrode surface. The practical application was carried out with spiked water samples originated from purified water and from three different local creeks, two of which are highly polluted with industrial and domestic effluents. The calculated detection limits ranged from 11 (for pure and unpolluted waters) to 39 ppb for the most contaminated sample. These low values indicate that such methodology can be conveniently applied in trace analysis.
Talanta, 2006
Redox behavior of three pesticides, namely isoproturon, carbendazim and methyl parathion was investigated electrochemically using hetropolyacid montmorillonite clay-modified glassy carbon electrode in the presence and absence of a surfactant, cetyl trimethyl ammonium bromide. A solution of 0.1 M H 2 SO 4 in 50% aqueous alcohol (pH 1.0) was found to be suitable medium for electroanalysis. Isoproturon exhibited one well-defined oxidation peak around 1.2 V along with one more oxidation and reduction peaks. Carbendazim showed only one well-defined anodic peak around 1.4 V. Methyl parathion exhibited one well-defined reduction peak around −0.26 V and the oxidation peak appeared around 0.510 V. In the second cycle, a new cathodic peak was found around 0.420 V. The presence of surfactant enhanced the peak current and hence stripping voltammetric determination procedures for all the three pesticides were developed. Square wave stripping mode was employed and the maximum current experimental conditions were arrived at. Calibration plot was made for all the three pesticides. The determination limit and standard deviations were arrived at. The applicability of the method was also verified in a soil sample and water analyte.
Contemporary voltammetric techniques and its application to pesticide analysis: A review
Materials Today: Proceedings, 2021
The objective of the paper is to access the usefulness of contemporary voltammetric methodologies using various classical and modified electrode system and surface-active agents for wide range of application. Although in industrial sector the voltammetric techniques have certainly lesser explored than spectroscopic, chromatographic and electrophoretic techniques but offer superior solution for specific tasks due to its qualitative as well as quantitively characterisation ability. Voltammetric methodologies are one of the emerging contemporary assay procedures that allows a easy and fast discrimination and its voltammogramic equivalence with a spectrum in spectroscopy provide ample information on the chemical characteristics of electro active species involved in redox processes. Application of voltammetry is widely explored and exploited in the fields of science and technology inclusive of environmental analysis of pesticides at commercial and residue levels (10 À12-10 À1 M). Optimisation of voltammetric response is critical to obtain credible and reliable interpretable data in suitable electrolyte-solvent system in applied potential range in electrochemical cell with suitable indicator, reference and counter electrode system. Recent development in chemically modified electrode in term of sensitivity, selectivity and diverse applications leads to revolution in voltammetry techniques. Recent trends revealed that such contemporary voltammetric methods are reasonably explored in pesticide analysis of variety of thiourea, benzimidazoles, organophosphorus, dithiocarbamates, triazines, carbaryl, organochlorine, etc. Diversity and complexity of the pesticide structures create electroanalytical possibility to explored reactions potential range from cathodic to anodic along with a number of explored voltammetric techniques involving Hg, amalgam, Au, glassy carbon, carbon paste and BDD Electrode its further modification for their determination. However, in recent intervals the classical voltammetric techniques have almost been vanished and are being substitute by more advanced voltammetric methodologies for numerous analytical and mechanistic studies.
Recent Developments in Electrode materials and Methods for Pesticide Analysis - An overview
Different types of electrode materials have been developed recently for the potential application in pesticide sensor analysis. These electrodes are employed for the determination of organophosphates, carbamates and methyl parathion. This short review article gives an overview of different analytical and electrochemical methods (High performance liquid chromatography, cyclic voltammetry, square wave voltammetry, differential pulse voltammetry and electron impedance spectroscopy) reported for the pesticide detection and new kinds of electrode materials including carbon nanomaterials, metal oxides, conducting polymers and clays based materials for the detection of environmentally and biologically toxic pesticides and herbicides. The recently developed electrode materials which are able to detect upto lower level concentrations of pesticides with high sensitivity and specificity have been reviewed. Real sample studies carried out in apple, cabbage, tap water and lake water were also overviewed.
Square wave voltammetric determination of diquat using natural phosphate modified platinum electrode
Arabian Journal of Chemistry, 2017
A platinum electrode modified with natural phosphate (NP) was evaluated as an electrochemical sensor for diquat (DQ) in aqueous medium. The electrode was prepared by the deposition of natural phosphate on the platinum surface. Diquat was preconcentrated on the surface of the modified electrode by adsorbing with natural phosphate and reduced at a negative potential in 0.1 M K 2 SO 4 solution. The influence of accumulation time and pH of the electrolytic solution were investigated. The calibration graph obtained under the optimized conditions was linear with a correlation coefficient of 0.9813 at levels near the detection limits up to at least 5.32 • 10 À9 mol L À1 with the relative standard deviation (RSD) lower than 3.37%. Interferences by some metals were investigated. Fe, Zn, Cu, MnO 4 and Hg apparently affected the peak currents P 1 and P 2 of diquat. The natural phosphate modified platinum electrode was applied to the determination of diquat in natural water samples. The results indicate that this electrode is sensitive and effective for the determination of diquat.
Journal of Hazardous Materials, 2007
A square wave voltammetry (SWV) method for the determination of trace amounts of paraquat at carbon paste electrode modified with natural phosphate (NP-CPE) is proposed. Paraquat was accumulated onto natural phosphate at open circuit potential from aqueous solution. The reduction peaks of paraquat were observed around −0.7 V and −1.0 V (versus SCE). The response of paraquat at NP-CPE related to: the concentration of this herbicide, preconcentration time, natural phosphate loading and measuring solution pH, was investigated. It was observed that the increase of the cathodic peak currents using SWV, under the optimized condition, is linear with the increase of paraquat concentration in the range from 2.3 × 10 −8 mol L −1 to 300 × 10 −8 mol L −1. The detection limit (DL, 3S.D.) and quantification limit (QL, 10S.D.) for peak 1 were about 7.8 × 10 −10 mol L −1 and 2.59 × 10 −9 mol L −1 , respectively, in pure electrolyte water with the relative standard deviation of 1.8% (n = 7). The proposed method was successfully applied to the determination of paraquat in real water samples with satisfactory results.