Construction of a High-Stability Electrochemical Immunosensor for Determination of Acetamiprid and Fipronil

Acetamiprid (ACE) and fipronil (FIP) are extensively applied broad-spectrum insecticides. They are recalcitrant to degradation and accumulate along food chains, creating prominent residual hazards to food security and ecological environments. Herein, a high-stability competitive electrochemical immunosensor was established for quantitative detection of ACE and FIP. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) characterized the layer-by-layer assembly of sensing interfaces, verifying the validity of competitive immune recognition. Under optimal conditions, the sensor exhibited linear ranges of 0.49–125.0 ng/mL for ACE and 0.49–62.5 ng/mL for FIP, with all determination coefficients (R2 > 0.99). The limits of detection (LODs) reached 0.33 ng/mL and 0.25 ng/mL, respectively. Spike-recovery detection on six fruit and vegetable matrices yielded recoveries of 84.63–100.80% with RSDs less than 7.8%, which confirmed excellent consistency between the immunosensor and standard LC-MS. This sensing platform combines fast response, high sensitivity, and superior stability, delivering a novel technical approach for rapid on-site screening of trace ACE and FIP residues in agricultural and environmental samples, and offering technical support for food safety supervision and pesticide risk assessment.