A novel strategy to precisely adjust partition coefficient, effectively eliminate matrix interference and achieve accurate and fast gold immunochromatographic assay of ethoxyquin in aquatic products

Ethoxyquin (EQ), a common antioxidant in animal feed and aquatic products, poses health risks such as hepatorenal damage and teratogenicity. Conventional detection methods, while sensitive, are often complex and costly. This study introduces a novel pH-dependent extraction strategy to mitigate matrix interference from lipid co-extracts in Gold Immunochromatographic Assay (GICA). This study introduces a pH-dependent extraction strategy leveraging EQ's LogD range, coupled with Plackett-Burman and Box-Behnken experimental designs, to rapidly establish a simplified pretreatment protocol. The method achieved a 10 μg/kg detection limit—below international thresholds—by eliminating lipid matrix interference through pH adjustment. The method's effectiveness was confirmed through validation and comparison with the Chinese national standard method using real samples. This work not only advances the rapid analysis of EQ in food safety monitoring but also provides a versatile framework for designing simplified pretreatment protocols for detecting highly non-polar compounds.