DESENVOLVIMENTO DE UMA METODOLOGIA ELETROANALÍTICA PARA A DETERMINAÇÃO DE GLIFOSATO EM AMOSTRAS AMBIENTAIS. / DEVELOPMENT OF AN ELECTROANALYTICAL METHODOLOGY FOR DETERMINATION OF GLYPHOSATE IN ENVIRONMENTAL SAMPLES

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

19/04/2012

RESUMO

This paper describes the development of an electroanalytical methodology for the determination of the pesticide glyphosate in environmental samples. The results obtained by square wave voltametry (SWV) in NaNO2 0,10 mol L-1 (pH 6,5) about hanging mercury drop electrode (HMDE) showed that glyphosate has not electroactive response. Thus, the electroactivity of glyphosate was obtained by complexation with Cu2+ ions. The complex formed Cu (II) glyphosate showed only a reduction peak at - 0,1 V with almost reversible process controlled by diffusion of the species on the electrode surface. The voltammetric and experimental parameters involved in the electrochemical reduction were optimized and the best responses were: NaNO2 supporting electrolyte of 0,10 mol L-1 at pH 6,5, concentration of Cu (II) of 2,61 x 10-7 mol L-1, pre-concentration time 120 sec. The parameters were SWV frequency = 100 sec-1, amplitude = 50 mV and increase of sweep = 6mV. After the system optimization, calibration curves were constructed and the detection limit (LD) and quantification limit (LQ) obtained were 22,04 μg L-1 0,42 and 73,46 μg L-1 1,41, respectively. The recovery tests showed values of 100,27% 1,96 in electrolyte and 99,12% 2,14 in water. Additionally, the methodology was applied for determination of glyfhosate in water sample collected in the creek from the Santa Clara, in the municipality of Candói/PR, with a value of 311,09 μg L-1 glyphosate. Interference study was performed from the humic acid and it was found that there was a complex between the Cu (II) and humic acid, shifting the potential for negative regions. The presence of humic acid with the complex Cu (II) glyphosate causes an increase in the current intensity also led to an increase in the width of the potential. Although the interference xi seen, the percentage recovery in the sample examined were above 99% so the glyphosate can be measured in samples of water by the proposed method.

ASSUNTO(S)

eletrodo de mercúrio voltametria de onda quadrada complexo cu (ii) - glifosato quimica mercury electrode square wave voltammetry the complex cu (ii) glyphosate

ACESSO AO ARTIGO

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