An anodically pretreated boron-doped diamond electrode surface for square-wave adsorptive stripping voltammetric quantification of the non-absorbable antibiotic rifaximin in the pharmaceutical formulation

This study presents an electroanalytical examination with the voltammetric technique for quantitatively evaluating rifaximin (RFX) using the non-modified boron-doped diamond (BDD) electrode. By utilizing cyclic voltammetry (CV) method, RFX illustrated only one well-defined, irreversible, adsorption-controlled by oxidation and reduction peak at about +0.64 V and +0.21 V, respectively, (vs Ag/AgCl) in 0.1 M HNO3 solution. The square-wave (SW) voltammetric technique examined the dependence of potentials and current intensities on the BDD electrode pretreatment, the nature of a supporting electrolyte, pH, and another characteristic. When the SW mode was used, a satisfactory linear response was achieved in 0.1 M HNO3 solution at +0.56 V (vs Ag/AgCl). The dynamic range is observed from 0.5 to 20.0 mu g mL-1 (6.36 x 10-7-2.54 x 10- 5 M) via a low limit of detection of 0.14 mu g mL-1 (1.7810-7 M). The applicability of the developed method for detecting RFX was exhibited in pharmaceutical formulation samples.