Ultra-sensitive glyphosate detection in soil and wastewater using Zn-zeolitic imidazolate framework-67/montmorillonite nanocomposite electrochemical sensor

Abstract

A novel electrochemical sensor for the determination of glyphosate (GLY) has been developed. It is based on a nanocomposite of zinc-based zeolitic imidazolate framework-67 and exfoliated montmorillonite (Zn-ZIF-67/Exf. MMt). The composite was synthesized by a hydrothermal method and characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and surface area analysis (BET). Incorporated into a modified graphite paste sensor (MGPS), the material provided high conductivity, large electroactive surface area (0.68 cm2), and low resistivity (75.0 Ω). Using square wave adsorptive cathodic stripping voltammetry (SW-AdCSV), the optimized sensor, containing 1.0% (Zn-ZIF-67/0.5 Exf. MMt) modified graphite paste sensor (MGPS), showed excellent electrochemical performance with a high electroactive surface area (0.68 cm2), and low resistivity (75.0 Ω). Under standard conditions, the sensor achieved a low detection limit of 0.009 nM (linearity range: 0.03-1.0 nM), and 0.015 nM (linearity range: 0.05–1.2 nM) in bulk, and spiked soil, respectively. This sensor offers a practical and highly sensitive tool for early detection of glyphosate, supporting environmental safety and sustainable agriculture.