Aminopropyltriethoxysilane functionalized hematite nanotube-based sensing platform for electrochemical detection of fenitrothion residues

<h2>Abstract</h2> Fenitrothion (FNT), a widely used organophosphorus pesticide, poses severe environmental and human health risks due to its high toxicity, making its trace-level detection in food and environmental samples critically important, thus emphasizing the need for advanced analytical methods to accurately monitor FNT levels. In this study, it was hypothesized that functionalizing hematite nanotubes (HNTs) with aminopropyltriethoxysilane (APTES) can enhance electron transfer kinetics and surface reactivity, thereby enabling the ultrasensitive electrochemical detection of FNT. To support this hypothesis, a glassy carbon electrode (GCE) was modified with APTES-functionalized HNTs (GCE/HNT/APTES) and systematically characterized using a combination of electrochemical analytical methods such as cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The proposed sensor exhibited excellent electrochemical performance with a wide linear detection range of 100 - 1 μM and 1 - 0.001 μM, a remarkably low detection limit of 0.14 nM, and a sensitivity of 1.3 μA/μM·cm². Stability and reproducibility were confirmed with <2% relative standard deviation, while recovery studies in real vegetable samples (eggplant, cucumber, tomato, and pointed gourd) demonstrated high accuracy, ranging from 95.87% to 105.97%. This is the first to report on the development of APTES-functionalized HNT as a sensing platform and its application in the quantification of FTN. These findings established APTES/HNT composites as a novel and highly effective sensing platform for the detection of FNT. The developed sensor offers a rapid, cost-effective, and portable approach for pesticide monitoring, providing significant potential for applications in food safety, agricultural management, and environmental protection.