Simultaneous detection of Pb2 + and Cd2+ in vegetables by g-C3N4@MWCNTs modified tin-based electrochemical sensor

Heavy metal contamination, especially Pb 2+ and Cd 2+ , poses severe risks to food safety and human health, creating an urgent need for rapid and sensitive detection methods. Herein, a novel tin-based electrochemical sensor with graphitic carbon nitride (g-C 3 N 4 ) and multi-walled carbon nanotubes (MWCNTs) modified glassy carbon electrode (GCE) was developed for the simultaneous detection of Pb 2+ and Cd 2+ in vegetables. The SnO 2 /g-C 3 N 4 @MWCNTs/GCE was systematically characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR). The synergistic effect of the g-C 3 N 4 @MWCNTs composite and the SnO 2 film effectively facilitated electron transfer and accelerated the response, enhancing sensing performance. Under optimal conditions, the linear range of the sensor for Pb 2+ and Cd 2+ was 10–400 μg·L −1 . The limits of detection (LODs) were 0.40 μg·L −1 and 0.61 μg·L −1 for Pb 2+ and Cd 2+ , respectively. In vegetable samples, the recoveries of Pb 2+ and Cd 2+ in spinach, lettuce, and cabbage were all within the range of 95–105 %. This study provides a new method to quickly, sensitively, and simultaneously detect Pb 2+ and Cd 2+ in vegetables. These findings expand the application of environmentally friendly tin-based electrochemical sensors for actual sample detection.