Rapid and sensitive detection of flubendiamide in grapes and tomatoes using a colloidal gold immunochromatography assay

In this study, we developed a monoclonal antibody (mAb)-based colloidal gold immunochromatography assay (CG-ICA) strip for the rapid and sensitive detection of flubendiamide (FBD) in food samples. Our anti-FBD mAb 2B1 was highly specific and had a half-maximal inhibitory concentration (IC₅₀) of 1.55 ng/mL under optimal conditions. It belongs to the IgG2a isotype and has a K_aff value of 1.52 × 10⁹ mol/L. The strip provided a visual detection limit of 50 ng/g for both grapes and tomatoes, with a cut-off value of 1,000 ng/g and these qualitative results were observed within 15 min. For quantitative analysis, the calculated detection limits were 6 ng/g and 5 ng/g in grapes and tomatoes, respectively. The average recoveries of FBD ranged from 88.8% to 111.8% in grapes and 94.5% to 110.6% in tomatoes. The proposed strip assay is highly practical for screening FDB in food samples.