Electrooxidation of trifloxystrobin at the boron-doped diamond electrode: electrochemical mechanism, quantitative determination and degradation studies

ABSTRACT

The boron-doped diamond (BDD) presents attractive electrochemical sensing characteristics that are useful in analytical applications based on voltammetry and amperometry. It has a wide potential window in aqueous solutions enabling the quantification of the fungicide trifloxystrobin, measured at +1744 mV (versus Ag/AgCl), by square-wave anodic voltammetry in a Britton–Robinson (BR) buffer (0.04 mol L^−1; pH 4.00)/acetonitrile 70/30% v/v. The activation of the electrode was made using galvanostatic chronopotentiometry and cyclic voltammetry (CV). The linear analyte addition curve, I_p (µA) = (1.0 × 10^–1 ± 4.8 × 10^–6) C (mol L⁻¹) + (8.8 × 10^–2 ± 1.1 × 10^–3); R² = 0.997, was obtained using amplitude of 40 mV, frequency of 30 Hz, step potential of 20 mV. The instrumental limit of detection (LOD) was 1.4 × 10^–7 mol L⁻¹ (0.058 mg L⁻¹) and the dynamic linear range covered three decades (up to 1 × 10^–5 mol L⁻¹ or 4.1 mg L⁻¹). The samples were analysed with recoveries about 80% in orange juice samples and from 92.4% to 104.0% in water samples. A study to evaluate potential interferences was made in the presence of other fungicides. Diagnostic studies indicated that oxidation of trifloxystrobin in aqueous medium at the surface of the BDD is irreversible, involving two steps, each one with two electrons. The UV degradation of trifloxystrobin was evaluated using the proposed electrochemical method and the kinetics of degradation established with half-life of 1.07 min.

KEYWORDS:

• Trifloxystrobin
• voltammetry
• boron-doped diamond electrode
• natural waters
• orange juice
• photodegradation

Acknowledgements

Aucelio thanks the Brazilian scientific agencies CNPq (474220/2013-3) and FAPERJ (E-26/201.406/2014 and E-26/110.740/2012) for research grants and scholarships. Almeida thanks CNPq for scholarship (141.071/2014-1), Dornellas thanks CNPq for scholarship (400.408/2015-5) and Toloza acknowledges his FAPERJ scholarship (E-26/200.435/2016).

Disclosure statement

No potential conflict of interest was reported by the authors.

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Funding

This work was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico: [Grant Numbers 302888/20132-6; 141.071/2014-1; 400.408/2015-5]; Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ): [Grant Numbers E-26/110.740/2012; E-26/201.406/2014; E-26/200.435].