Fast and sensitive metronidazole determination by means of voltammetry on renewable amalgam silver based electrode without the preconcentration step

Abstract

Application of cyclic renewable amalgam silver-based electrode (Hg(Ag)FE) for sensitive metronidazole detection by the differential pulse voltammetry (DPV) is described. The unique properties of the Hg(Ag)FE such as the relative large surface area and its fast and very simple renewal were fully utilized for sensitive measurements. Compared with the classical hanging mercury drop electrode (HMDE), the renewable Hg(Ag)FE significantly increases the reduction peak current of metronidazole because of its large surface area. The effects of various factors for the metronidazole determination such as: pulse height and width, step potential, surface area of the working electrode, and basic electrolyte composition are optimized. The obtained calibration graph is linear from 0.1 (17 ?g L-1) to 2 ?M (342 ?g L-1) with correlation coefficient 0.999. For the Hg(Ag)FE with the surface area of 10.1 mm2 the limit of detection (LOD) is 20 nM (3.4 ?g L-1). The repeatability of the method at a concentration of the analyte of 0.5 ?M (5.6 ?g L?1), expressed as relative standard deviation (RSD) is 2.1 % (n = 7). The proposed method was successfully applied and confirmed by studying recovery of metronidazole from spiked samples.