Abstract
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 Ceara State, Brazil. The obtained
detection limits ranged from 7.47 x 10(-9) to 1.80 x 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 Mulliken'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.
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