Development of advanced voltammetric method for telmisartan and study of oxidation mechanism on boron-doped diamond electrode

This work describes the development of a voltammetric method for the determination of telmisartan (TEL) employing an anodically pretreated boron-doped diamond electrode (AP-BDDE). In this electrode, TEL presented an irreversible peak at +1.33 V (vs. Ag/AgCl), which was associated with its oxidation involving two electrons and two protons. From the combination of electrochemistry and NMR spectroscopy data, it was possible to propose for the first time the reaction of oxidation for the TEL molecule onto the BDDE. Parameters recommended by validation guidelines were evaluated to validate the proposed method. Using differential pulse voltammetry, a linear plot was obtained for TEL in the concentration range 10-109 nmol L^-1 in acetate buffer (pH 5.0), with a limit of detection of 0.16 nmol L^-1. The selectivity of the methods was assessed against urine and water interferers, showing relative standard deviation values below 8%. The proposed method was successfully applied to pharmaceutical, environmental, and biological samples, exhibiting profiles consistent with green analytical chemistry, as confirmed by an assessment using the AGREE approach from the literature.