Highly sensitive electrochemical detection of monosodium glutamate and nitrite on a binary metal (FeZnO) nanocomposite†

This study presents the synthesis of an iron functionalized zinc oxide nanocomposite (FZO) by a simple hydrothermal method. The synthesized FZO nanoparticles were characterized by Fourier transform infrared (FT-IR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), Brunauer–Emmett–Teller (BET) and transmission electron microscopy (TEM). The histogram plot of the particle size distribution indicates that the average particle size was ∼27 nm. To assess their sensing ability of monosodium glutamate (MSG) and nitrite (NO₂⁻), cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometry were employed. The FZO/GCE electrode showed outstanding efficacy in sensing both the target molecules, with a notable linear detection range, high sensitivity, and low detection limit. For MSG, the sensor exhibited a linear range from 10 to 100 μM, a sensitivity of 4.91 μA mM⁻¹ cm⁻², and a detection limit of 1.41 μM and the NO₂⁻ sensing abilities included a linear range of 1 μM to 5.848 mM, a sensitivity of 55 μA mM⁻¹ cm⁻², and a detection limit of 1.93 μM. Also, this electrochemical sensor shows a good recovery rate and RSD in the range of 84 to 97.64% and 0.08 to 0.43%, respectively, for the analysis of MSG and NO²⁻ in the real samples. From the obtained results the electrode confirmed high selectivity, excellent stability, reproducibility, and practical applicability for detecting MSG, and NO₂⁻. These findings make it a valuable electrode for accurate and portable sensing of these analytes.