Systematic Development and Validation of a Green Voltammetric Method Employing a Carbon‐Black Paste Electrode for Doxazosin Determination

Doxazosin mesylate (DOX) is an α 1 ‐adrenergic receptor antagonist commonly used to treat hypertension or also to benign prostatic hyperplasia. Due to its narrow therapeutic window, precise quantification is essential for safety and effectiveness. This study details the development and validation of a novel voltammetric method using a carbon black paste electrode to determine DOX in pharmaceutical, biological, and environmental samples. DOX presented an irreversible oxidation peak (OP 1 ) at +1.00 V, a quasireversible reduction peak (RP 1 ) at +0.06 V followed by the quasireversible oxidation peak (OP 2 ) + 0.15 V (vs. Ag/AgCl 3.0 mol L −1 ). The method presented displayed a linear range of 0.099–1.283 μmol L −1 , and an limit of detection (LOD) of 0.028 μmol L −1 employing the square‐wave voltammetry in phosphate buffer solution pH (3.0), showing that the developed method is more sensitive than the chromatographic and spectrophotometric methods described in the literature. The method showed adequate selectivity, precision, and accuracy for the determination of DOX in tablets, urine sample, and water samples. Furthermore, the Analytical GREEnness calculator was used, obtaining high greenness score for biological/environmental samples (0.68) and pharmaceutical samples (0.65), demonstrating that the developed method is an environmentally sustainable alternative, aligning with the principles of Green Analytical Chemistry, and holds promise for more ecologically friendly analytical applications.