Cetyltrimethylammonium bromide-gold nanoparticles composite modified pencil graphite electrode for the electrochemical investigation of cefixime present in pharmaceutical formulations and biology

Recent Developments in Voltammetric Analysis of Pharmaceuticals Using Disposable Pencil Graphite Electrodes

“…The electrochemical characterization of bare and modified electrodes was usually performed by CV [87,88,117,124,125,129] and electrochemical impedance spectroscopy (EIS) using [Fe(CN) 6 ] 3−/4− as a redox probe and KCl as a supporting electrolyte [17,20,37,41,43,45,47,53,56,57,59,[63][64][65]69,80,85,87,90,105,117,124,125,127,131,132,136,[141][142][143]147], but [Ru(NH 3 ) 6 ] 3+/2+ was also used [38].…”

“…CV carried out at different scan rates was most often employed to calculate the electroactive surface area (A ea ) of bare or different modified electrodes while considering the slope of the regression equation corresponding to the I p = f(v 1/2 ) plot, where I p (A) repre-sents the peak current and v is the potential scan rate (V/s) [16,20,38,39,41,[43][44][45][46][47][48][49]53,56,59,64,67,72,74,82,85,87,88,106,[124][125][126]128,141].…”

“…Generally, the electrode's electroactive surface area is higher than the geometrical one due to the porosity [40] or irregular surface morphologies. Moreover, the immobilization of various types of modifiers on the PGE surface resulted in an enhanced electroactive surface area [17,63,69,85,110,136,141]. For example, the surface areas of the AuNPs/P(Lmet)/PGE [130] and of the rGO/PWA/PGE [64] were about twofold higher than that of the corresponding bare PGE.…”

“…A decrease in ∆E suggests faster electron transfer rates and therefore a more reversible electrode process, while larger peak currents indicate an enhanced A ea and better electrocatalytic activity of the electrode [10,[45][46][47]72,109,131]. Most studies revealed that PGE modification resulted in improved performance characteristics [37,85,128,136,141,147], such as a decrease in ∆E p from 440 mV for the PGE to 80 mV for the Chti/Sn/PGE [69] or improved electrochemical properties in the order of PGE < SNDGr/PGE < Cu-MOF/SNDGr/PGE due to enhanced peak currents and lowered ∆E p [63].…”

“…Thus, the larger semicircle indicates a high interfacial electron transfer resistance, whereas a small semicircle indicates a lower resistance, increased conductivity, and faster electron transfer. Usually, the ET [43,56,80] or modified electrodes employed [20,36,37,[45][46][47]53,57,59,61,[63][64][65]67,68,85,90,92,105,110,113,117,130,132,136,[141][142][143][144]147,148] in pharmaceutical quantification presented a much lower Rct and thus a higher electron transfer capability in comparison with the bare PGE or the electrodes modified during the different steps of the manufacturing process. For example, EIS measurements emphasized that by covering the PGE with MIP/sol-gel, the Rct increased due to the surface passivation and decreased after potentiostatic deposition of N-doped graphene [127], AuNPs [91], or phosphotungstic acid/reduced graphene oxide (PWA/rGO) [65] due to the electronconducting properties of the nanomaterials.…”