A portable 3D-printed lab-on-a-chip device for on-site monitoring of thiamethoxam residue in food samples.

Unexpected interferences from the food matrix pose challenges to achieving high-performance on-site monitoring of pesticide residues. In this study, we employed 3D printing technology to fabricate a miniaturized lab-on-a-chip (LOC) device for in-situ sample pretreatment. Serving as the analytical component, a lateral flow immunochromatographic strip was developed for thiamethoxam, a representative neonicotinoid insecticide. Results showed that the composite LOC device enabled on-site determination of thiamethoxam in 13 different food samples using a multi-step analysis approach. Similar to the buffer-based calibration curve (IC: 0.11 ng·mL), the matrix-based calibration curves for celery (IC: 0.15 ng·mL) and cucumber (IC:0.10 ng·mL) samples exhibited ultrahigh sensitivities, with a total analysis time within 15 min. The average recovery rates were 87.2 % ∼ 107.4 %, with relative standard deviations of 2.1 % ∼ 7.6 % at the spiked levels of 1 and 5 ng·g. Furthermore, this LOC device was applied to unknown food samples, achieving excellent accordance with LC-MS/MS confirmation.