Fabrication of bismuth oxide-modified pencil graphite sensors for monitoring the hazardous herbicide diuron

Abstract

In this work, a bismuth oxide/pencil graphite electrode (Bi₂O₃/PGE)-based ultrasensitive voltammetric sensor is reported for the quantification of the herbicide diuron (DU) in vegetable samples. A HB pencil lead of diameter 2.0 mm was applied to prepare the electrode. Bismuth oxide nanopowder of the size range 1–10 μm was used. The prepared Bi₂O₃/PGE was characterized by different techniques such as energy-dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). A linear calibration curve was plotted in the range of 5.0–160.0 ng mL⁻¹ in a BR buffer (pH 2.5) solution. The sensitivity of the fabricated sensor was calculated to be 2.80 ng mL⁻¹. The suggested sensor indicated higher sensitivity towards the detection of DU in a small-sized whole-tomato sample with 99.9% recovery.