Modularly integrated synergistic SERS strategy for ultra-trace detection of imidacloprid in fresh fruit and vegetable juices

A reliable IMIPCs–AMoO 2 /C SERS analytical method was established. • Validated results were acceptable for IMI in fresh fruit and vegetable juices. • The method displayed good linear correlation, low LOD, trueness and precision. • The mechanisms of a modularly integrated synergistic strategy were explored. • Rapid detection of trace levels of IMI in the sample was achieved (10 min). Imidacloprid (IMI), a first-generation neonicotinoid insecticide, is taken up by plants and distributed to edible parts owing to its systemic transport properties. This leads to its residues in fruit and vegetable juices, posing a potential food safety risk. Herein, we report a modular integrated synergistic SERS strategy for reliable, efficient and selective detection of IMI. An IMI-imprinted polymer-pesticide carb (IMIPCs) cartridge was designed for recognition, purification, and enrichment. The AMoO 2 /C SERS substrate, optimised through annealing, aligns its bandgap with the excitation wavelength, while IMI adsorption induces band bending and triggers charge-transfer resonance, enabling signal amplification. Under optimised conditions, the method exhibits excellent linearity from 0.500 ng/mL to 50.0 ng/mL, a low detection limit of 0.0904 μg/kg, and high accuracy in spiked typical juice matrices (tomato, celery, apple, and mixed juices), with recoveries of 92.7%–98.1% (RSD%, 0.332%–2.50%) and no significant difference compared with the HPLC method at the 95% confidence level. Application to twenty real samples collected from the market, including fruit and vegetable juice samples such as kiwi, kale, banana, and orange juices and their mixtures, demonstrated good selectivity, reliability, and reproducibility, with residue levels detected in the ppb range. Overall, this LEGO-inspired SERS method provides a simple, efficient and highly selective analytical strategy for monitoring IMI residues in fruit and vegetable juices, and can serve as a supplementary screening tool for routine food safety monitoring of such juice products. Its applicability to complex high-fat or protein-rich matrices, such as milk-based or nut-based beverages, remains to be further validated through subsequent research. Download: Download high-res image (199KB) Download: Download full-size image