Glyphosate Determination in Soil, Water and Vegetables Using DPV Optimized by Response Surface Methodology

Reinaldo F. Teófilo¹, Efraim L. Reis^1,*, César Reis¹, Gilmare A. da Silva¹, José F. Paiva² and Lauro T. Kubota³

¹ Departamento de Química, Universidade Federal de Viçosa, UFV, 36570-000, Viçosa, MG, Brasil

² Departamento de Química, Universidade Federal de Ouro Preto, UFOP, 35400-000, Ouro Preto, MG, Brasil

³Instituto de Química, Universidade Estadual de Campinas, UNICAMP, 13084-971, Campinas, SP, Brasil

 

Received 13^th November 2007; accepted 19^th April 2008

 

 

Abstract

A voltammetric procedure optimized by experimental design for glyphosate determination in soil, water and vegetable samples is described. The voltammetry experiments were performed using a hanging mercury drop electrode (HMDE). The DPV variables involved in the optimization process were: voltage step, pulse amplitude, pulse interval, voltage step time and concentration of the supporting electrolyte. A full 2⁵ factorial design was chosen to evaluate these effects. From the results obtained by the factorial design the three most important factors were determined. These variables were evaluated with a central composite design. Under the optimized conditions, the operational range was from 0.050 to 100.0 mg dm^-3 and the detection and quantification limits were 14 and 48 µg dm^-3, respectively. The optimized method was successfully applied to glyphosate determination in soil, water and vegetables after purifying with an ion exchange resin and derivation.

 

Keywords: glyphosate, SWV, experimental design, voltammetry.

 

 

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* Corresponding author. E-mail address: efraim@ufv.br