Abstract
Potentiodynamically fabricated poly(alizarin red s) modified GCE was characterized using CV and EIS techniques. In contrast to the cyclic voltammetric response of the unmodified GCE for metronidazole, an irreversible reduction peak with three-folds of current enhancement and reduced overpotential at the poly(alizarin red s) modified GCE showed the catalytic effect of the modifier towards reduction of metronidazole. While observed peak potential shift with increasing pH (4.0-10.0) indicated the involvement of protons during the reduction of metronidazole, peak potential shift with scan rate (20-300 mV s-1) confirmed the irreversibility of the reduction reaction of metronidazole at the modified GCE. A better correlation for the dependence of peak current on scan rate (r2 = 0.9883) than on square root of scan rate (r2 = 0.9740) supplemented by slope value of 0.38 for plot of log(current) versus log(scan rate) indicated the reduction reaction of metronidazole at the surface of the modified electrode was predominantly adsorption controlled. Under the optimized method and solution parameters, reductive current response of tablet sample showed linear dependence on spiked standard concentration in a wide range (0-125 μM) with excellent determination coefficient r2, LoD and LoQ of 0.9991, 0.38, and 1.25 μM, respectively. Spike recovery of 97.9% and interference recovery of 96.2-97.5% in the presence of 21.28 and 31.92 μM of uric acid and ascorbic acid validated the applicability of the present method for determination of metronidazole in tablet formulation. The metronidazole content of the tested tablet formulation using standard addition method was found to be 97.6% of what is claimed by the tablet manufacturer making the developed method an excellent potential candidate for its applicability to determine metronidazole in real samples with complex matrix.
Highlights
The present study describes the application of an accurate, precise, and selective standard addition method based on poly(Alizarin red S) modified glassy carbon electrode (PARS/GCE) for determination of MTZ in tablet sample, which to the best of our knowledge has not been communicated previously for the same
While cyclic voltammetry was used to deposit polymer film on the surface of GCE, characterize the polymer film, and investigate behavior of MTZ at the modified electrode, effect of scan rate and solution pH on both peak current and peak potential; square wave stripping voltammetry was employed for the quantitative analysis of MTZ in tablet sample
While cyclic voltammetry (CV) results showed the modification of the electrode surface by a redox active material, electrochemical impedance spectroscopy (EIS) results confirmed surface modification by a more conductive material
Summary
Poly(alizarin red S) modified GCE for stripping voltammetric determination of metronidazole in tablet sample. Capillary electrophoresis [8], high performance liquid chromatography [9], titrimetry [10], and spectrophotometry [11] are among the commonly reported methods for determination of MTZ in pharmaceutical samples Most of these methods are known to have limitations in simplicity, cost-effectiveness, easy access, and environmental friendly [12]. The present study describes the application of an accurate, precise, and selective standard addition method based on poly(Alizarin red S) modified glassy carbon electrode (PARS/GCE) for determination of MTZ in tablet sample, which to the best of our knowledge has not been communicated previously for the same. CHI760E Electrochemical Workstation (CHI Instruments, Austin, Texas, USA), pH meter (Adawa model AD800), electronic balance (Denver Instrument), and refrigerator were used for electrochemical data acquisition, pH adjustment, weighing mass and preserving sample, respectively
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