Electrochemical Elimination of the Pesticide Methylparathion in an Aqueous Medium

Manzanilla‐Cano, José A.; Reyes-Salas, E. O.; Barceló‐Quintal, Manuel H.

doi:10.1080/03067319908047325

Cited by 19 publications

(12 citation statements)

References 25 publications

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“…For 1.8<pH<5, two peaks were observed, one very well-defined and other ill-defined, 10 named peaks 1 and 3, respectively, in the present work. As suggested in the literature, [10][11][12] four and two electrons were involved in those redox process, respectively for peaks 1 and 3. In neutral and alkaline media, a process involving four electrons was observed in the reduction of this pesticide [10][11][12] (named peak 2 in the present work).…”

Section: Electroanalytical Proceduresmentioning

confidence: 66%

“…As suggested in the literature, [10][11][12] four and two electrons were involved in those redox process, respectively for peaks 1 and 3. In neutral and alkaline media, a process involving four electrons was observed in the reduction of this pesticide [10][11][12] (named peak 2 in the present work). For pH>8, hydrolysis of methylparation takes place, which affects the current intensity values, turning them time and pH dependent.…”

Section: Electroanalytical Proceduresmentioning

confidence: 86%

“…[10][11][12] In very acidic medium (pH<1.8) only one peak was detected and six electrons were exchanged in the redox reduction of the nitroaromatic group. 10 In our study the electrochemical behavior of methylparathion was studied only at pH above 2.0. For 1.8<pH<5, two peaks were observed, one very well-defined and other ill-defined, 10 named peaks 1 and 3, respectively, in the present work.…”

Section: Electroanalytical Proceduresmentioning

confidence: 99%

“…10 In our study the electrochemical behavior of methylparathion was studied only at pH above 2.0. For 1.8<pH<5, two peaks were observed, one very well-defined and other ill-defined, 10 named peaks 1 and 3, respectively, in the present work. As suggested in the literature, [10][11][12] four and two electrons were involved in those redox process, respectively for peaks 1 and 3.…”

Section: Electroanalytical Proceduresmentioning

confidence: 99%

“…4 Despite its lower selectivity and sensitivity, in some cases, when compared to chromatography, the electroanalytical procedures have several advantages such as their low cost and the possibility of analysis without the need of extraction or pre-treatments, as well as the short time required for the analysis. [5][6][7] Some features of the electrochemical behavior of the organophosphorous insecticide methylparathion over mercury electrodes have been already studied, [8][9][10][11][12] but there is no complete electroanalytical method established for its determination in natural samples, using this electrode.…”

Section: Introductionmentioning

confidence: 99%

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Electroanalytical procedure for the determination of methylparathion in soil suspensions and its application for sorption studies with Brazilian soils

Castanho¹,

Vaz²,

Machado³

2003

J. Braz. Chem. Soc.

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A técnica de polarografia de pulso diferencial foi usada para estabelecer um procedimento eletroanalítico para a determinação do inseticida organofosforado parathion metílico (tiofosfato de dimetilparanitrofenila) em amostras de solo. Foram observados 3 picos de redução do metilparathion sobre eletrodo de mercúrio, em função do pH da solução. O pico mais catódico (Ep = -0,55 V), observado apenas em pH's maiores que 5,0, foi selecionado para as determinações analíticas. O limite de detecção encontrado foi de 1,93x10 -8 mol L -1 para água pura e de cerca de 8x10 -8 mol L -1 para as amostras de solo, com velocidade de varredura de 2 mV s -1 e pH da solução de 6,75. O procedimento eletroanalítico desenvolvido foi utilizado para a obtenção de isotermas de sorção do parathion metílico em 3 solos do Estado de São Paulo, com distintos teores de argila, matéria orgânica e pH. O modelo de isoterma de Freundlich apresentou um excelente ajuste aos dados experimentais e os coeficientes de Freundlich (K F ) obtidos para cada solo apresentaram valores entre 7 e 29 L kg -1 , sendo considerados como de baixa a média capacidade de sorção nos solos estudados, de acordo com o critério do IBAMA (Instituto Brasileiro de Meio Ambiente e dos Recursos Renováveis). Os teores de matéria orgânica e argila dos solos foram os fatores que mais influenciaram a sorção do metilparathion nesses solos.The differential pulse polarography technique was used to establish an electroanalytical procedure for the determination of the organophosphorous insecticide methyl parathion (O,O-dimethyl O-(4-nitrophenyl) phosphorothioate) in soil samples. Three reduction peaks were observed in mercury electrodes as a function of the solution pH. The more cathodic peak (E p = -0.55V), only observed for pH values higher than 5.0, was chosen for the analytical determinations. The limit of detection was 1.93x10 -8 mol L -1 for pure water and about 8x10 -8 mol L -1 for soil suspensions with a scan rate of 2 mV s -1 and a pH of 6.75. The electroanalytical procedure developed was applied for the determination of sorption isotherms of methylparathion on 3 soils from São Paulo State, Brazil, at different pH and diverse amounts of clay and organic matter. The experimental data were fitted using the Freundlich isotherm model and the Freundlich coefficients (K F ) obtained for each soil varied from 7 to 29 L kg -1 , representing a low to medium sorption capacity, according to the IBAMA (Brazilian Environmental Protection Agency) standards. The amounts of organic matter and clay were the most important soil parameters controling the sorption of methylparathion by these soils.

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