Direct electrochemical analysis of dexamethasone endocrine disruptor in raw natural waters

Abstract

Este trabalho descreve uma metodologia eletroanalítica, utilizando voltametria adsortiva de onda quadrada, que foi aplicada com êxito na determinação direta de resíduos de dexametasona em águas naturais brutas utilizadas no abastecimento público do Estado do Ceará, Brasil. Os limites de detecção obtidos variaram entre 7,47 × 10 -9 e 1,80 × 10 -8 mol L -1 para as três matrizes de águas naturais brutas avaliadas. Os valores percentuais médios de recuperação (98,86% ± 0,72), repetibilidade (0,32% ± 0,05) e reprodutibilidade (0,91% ± 0,20) foram significativos, reafirmando a sensibilidade do procedimento. A energia dos orbitais LUMO e as cargas atômicas de Mülliken foram calculadas usando o funcional BLYP/DNP. Os resultados teóricos, aliados aos critérios de diagnóstico da voltametria de onda quadrada, indicam que o mecanismo redox da dexametasona está associado a processos de redução quase-reversível e irreversível dos grupos cetona localizados em C-20 e C-3, respectivamente. This paper describes an electroanalytical methodology using square-wave adsorptive voltammetry, which has been successfully applied for the direct determination of dexamethasone residues in raw natural waters used for the public supply of the Ceará State, Brazil. The obtained detection limits ranged from 7.47 × 10 -9 to 1.80 × 10 -8 mol L -1 for the three matrices of raw natural waters evaluated. High percentages of average recovery (98.86% ± 0.72), repeatability (0.32% ± 0.05) and reproducibility (0.91% ± 0.20) were obtained in these samples, reaffirming the sensitivity of the procedure. Energy of the LUMO orbitals and Mülliken's atomic charges were calculated using the functional BLYP/DNP. The theoretical results allied to the diagnostic criteria of the square-wave voltammetry indicate that the dexamethasone redox mechanism is associated to the quasi-reversible and irreversible reduction process of the ketone groups located at C-20 and C-3, respectively.

Biosensor based on multi-walled carbon nanotubes paste electrode modified with laccase for pirimicarb pesticide quantification

“…This fact highlights the electroanalytical feature of the developed TvL (composition) /MWCPE biosensor for quantification of PMB, since the redox process of this pesticide occurs usually at high oxidation [44] or reduction [15] potentials. Studies performed by CV showed a linear relationship between the peak current and the square root of scan rate indicating that the mass transport of the analyte at the biosensor/solution interface is controlled by diffusion [21,22,45]. Over time, the quasi-reversible couple has a gradual reduction in its peak current, while the reduction of p-benzoquinone (at À0.070 V) is enhanced and stabilized along time which was used as analytical signal.…”

Electrochemical Determination of Dexamethasone by Graphene Modified Electrode: Experimental and Theoretical Investigations

“…There have been limited studies using electrochemical techniques for determination of the DEX 5,14–21 . Initially, Jeyaseelan et al .…”

Chitosan-magnetite nanocomposite as a sensing platform to bendiocarb determination

“…The optimization of the proposed electroanalytical methodology, obtaining values for detection and quantification limits (LoD and LoQ, respectively) and evaluation of precision and accuracy were performed as described in the literature in our previous work [48,49].…”

“…To evaluate the applicability of the proposed methodology, natural water samples were analyzed using the proposed electroanalytical methodology for matrix effect evaluation. Those water samples were collected from Acarape do Meio dam and Gavião dam as described in the literature in our previous works [48,53].…”