Highly sensitive and stable electrochemical detection of fenitrothion residues in tea samples based on MWCNTs-modified holey reduced graphene oxide

Fabricated a HrGO/MWCNTs-based electrochemical sensor for sensitive FT detection. • Enhancing electrocatalytic activity via synergistic effect between HrGO and MWCNTs. • Exhibiting good reproducibility, strong anti-interference and excellent stability. • The sensor shows a wide linear range (0.008–10.0 μM) and an ultralow LOD (6.6 nM). Sensitive and reliable detection of fenitrothion (FT) is still a challenge owing to its poor intrinsic electrochemical activity and the lack of stable advanced functional material. Herein, a novel electrochemical sensor was successfully fabricated using holey reduced graphene oxide/multi-walled carbon nanotube (HrGO/MWCNTs) nanocomposites as the functional modification material. The synergistic effect between HrGO and MWCNTs efficiently enhances electrocatalytic response and stability to the reduction of FT. The developed sensor achieves sensitive FT detection over two linear range of 0.008–1.0 μM and 1.0–10.0 μM, with a low limit of detection of 6.6 nM. The sensor also presents favorable reproducibility, high anti-interference performance, and excellent long-term stability. Moreover, the proposed method was successfully utilized for the determination of FT residue in commercial white, green, and black tea powder samples, with recoveries ranging from 90.93% to 100.9% and relative standard deviation (RSD) values of 0.5–4.8%. Its accuracy is in good agreement with that of conventional high-performance liquid chromatography, confirming that this sensing platform holds great promise for practical FT residue analysis.