Academic literature on the topic 'Differential-pulse voltammetry (DPV)'

The voltammetric behavior of three cephalosporins: ceftazidime, cefuroxime-axetil and ceftriaxone has been examined in pH range 2.0-8.0 by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), using a hanging mercury drop electrode (HMDE). The effect of pH of the electrolyte solution and scan rate on the peak currents and peak potentials was examined. The nature of the electrode reduction process in acid solution was found to be diffusion controlled for ceftazidime and cefuroxime-axetil, but strongly influenced by adsorption in the case of ceftriaxone reduction. The adsorption and reorientation of the ceftriaxone molecule at the electrode surface caused instability of the voltammetric signal and disabled its determination in the acid medium. Ceftriaxone adsorption decreased with the increase of pH, and at pH>7 the reduction process became diffusion controlled. Based on this study, DPV method was developed, validated and suggested for determination of ceftazidime at pH 2.0, cefuroxime-axetil at pH 3.5 and for ceftriaxone at pH 8.0. Linear concentration ranges, limits of detection (LOD) and quantification (LOQ) were determined. The method was applied for determination of cephalosporins in pharmaceutical dosage forms: Ceftazidime powder, Ceroxim tablets and Longaceph powder for injection solution.

Hesperidin (HESP) is a plant bioflavonoid found in various nutritional and medicinal products. Many of its multiple health benefits rely on the compound’s antioxidant ability, which is due to the presence of oxidizable hydroxyl groups in its structure. Therefore, the present study aimed to investigate the electrochemical behavior of HESP at a cheap, disposable pencil graphite electrode (PGE) in order to develop rapid and simple voltammetric methods for its quantification. Cyclic voltammetric investigations emphasized a complex electrochemical behavior of HESP. The influence of the electrode material, solution stability, supporting electrolyte pH, and nature were examined. HESP main irreversible, diffusion-controlled oxidation signal obtained at H type PGE in Britton Robinson buffer pH 1.81 was exploited for the development of a differential pulse voltammetry (DPV) quantitative analysis method. The quasi-reversible, adsorption-controlled reduction peak was used for HESP quantification by differential pulse adsorptive stripping voltammetry (DPAdSV). The linear ranges of DPV and DPAdSV were 1.00 × 10−7–1.20 × 10−5 and 5.00 × 10−8–1.00 × 10−6 mol/L with detection limits of 8.58 × 10−8 and 1.90 × 10−8 mol/L HESP, respectively. The DPV method was applied for the assessment of dietary supplements bioflavonoid content, expressed as mg HESP.