Electroanalytical determination of carbendazim and fenamiphos in natural waters using a diamond electrode Rafaela F. França a , Hueder Paulo M. de Oliveira b , Valber A. Pedrosa c , Lucia Codognoto d, ⁎ a Universidade Camilo Castelo Branco, São José dos Campos — SP, Brazil b Centro de Ciências Químicas, Farmacêuticas e de Alimentos, Campus Capão do Leão, Universidade Federal de Pelotas, RS, Brazil c Institute of Bioscience, Department of Chemistry and Biochemistry, UNESP, Botucatu, SP, Brazil d Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Departamento de Ciências Exatas e da Terra, Universidade Federal de São Paulo, Rua Prof. Artur Riedel, 275 — Bairro Eldorado, Diadema CEP: 09972-270, SP, Brazil abstract article info Article history: Received 17 February 2012 Received in revised form 16 May 2012 Accepted 21 May 2012 Available online 26 May 2012 Keywords: Pesticide Diamond electrode Carbendazim Fenamiphos Water analysis In this study, a method for electroanalytical determination of carbendazim (CBZ) and fenamiphos (FNP) in natural and spiked water was developed using square wave voltammetry in Na 2 HPO 4 0.1 mol L -1 as supporting electro- lyte. The calibration curve for carbendazim detection presented good linearity in the concentration range of 0.50 to 15.0 μM, with a sensitivity of 0.080 A/mol L -1 and a linearity of 0.998. The oxidation of fenamiphos on BDD elec- trode shows a dynamic range of concentration of 0.5 to 25.0 μM and sensibility of 0.14 A/mol L -1 . The recovery experiments showed values between 70 and 100% for spiked samples thus indicating the feasibility of the electro- analytical methodology to quantify CBZ and FNP in pure or natural waters. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Brazil is one of the world leaders in pesticide consumption and ex- posed workers are numerous and diversified. Acute poisonings are just the most visible aspect of pesticide impact on human health and few studies are available on acute pesticide exposure in poisoned subjects [1,2]. Recently, the FDA had detected low levels of car- bendazim in some orange juice products [3]. Due to the high toxicity of carbendazim rapid detection of those toxic agents has become in- creasingly important for homeland security and health protection in the entire world [4]. New analytical tools for pesticide detection are needed to provide an easy, simple and cheap alternative by local agencies to protect and enhance environmental assets. Over the past years, carbendazim has been used for the control of a wide range of fungal diseases such as mold, spot, mildew, scorch, rot and blight in a variety of crops [5–7]. It is frequently sold in combination with other fungicides such as fenamiphos. Both pesticides are widely used in agriculture to control soil pests. Recently toxicology studies suggesting that both pesticides have potential for acute and chronic ef- fects on human health, for groundwater contamination and for hazards to worker safety [8]. However, as far as we know, there are no methods reported in the literature for the simultaneous determination of carbendazim and fenamiphos in natural water without a previous sep- aration and preconcentration step. The most common approach has used chromatographic techniques to quantify both pesticides [9–11]. However, these methods require expensive instrumentation, using ex- haustive pretreatment procedure and professional operators, which limit their application for real-time detection of these compounds. Moreover, they usually involve the manipulation of a large amount of organic solvents, with the use of hundreds of milliliters of solvent being common for the treatment of just one sample. The recovery and disposal of these solvents are sometimes difficult and incomplete. In this way, pesticide residues can easily enter the atmosphere with haz- ardous effect to the environment and/or to the laboratory/industry staff [12,13]. Electrochemical methods for detection and quantification of pesti- cides have attracted a crescent amount of attention so far. This is mainly due to the low cost and fast analysis time that can be achieved using these techniques, as well as the possibility to perform the analysis in environmental matrices, without requirements of separations and clean-up procedures. Thin films of boron-doped diamond (BDD) have emerged as excellent electrode materials for several electrochemical applications, especially electroanalytical ones, mainly due to properties such as a wide potential window in aqueous solutions (up to 3 V), low background currents, low adsorption, and low sensitivity to dissolved oxygen [14–17]. Studies of electroanalysis, particularly for quantitative detection of trace amounts of harmful compounds in polluted water, have been performed by using BDD electrodes on the basis of their Diamond & Related Materials 27–28 (2012) 54–59 ⁎ Corresponding author. Tel.: + 55 11 3319 3300; fax: + 55 11 4043 6428. E-mail address: lucia.codognoto@unifesp.br (L. Codognoto). 0925-9635/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.diamond.2012.05.010 Contents lists available at SciVerse ScienceDirect Diamond & Related Materials journal homepage: www.elsevier.com/locate/diamond