Rational hapten design enables monoclonal antibody-based immunoassays for class-selective detection of phthalate esters in edible oils.

Phthalate esters (PAEs) are frequently detected in edible oils, necessitating rapid detection methods. However, the small molecular size and high structural similarity of PAEs make it challenging to develop antibodies that combine analytical sensitivity with group-selective recognition. Herein, a monoclonal antibody (mAb) with group-selective recognition toward dibutyl phthalate (DBP), diallyl phthalate (DAP), and diethyl phthalate (DEP) was generated through rational hapten design guided by computational analysis. Based on this mAb, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and a colloidal gold immunochromatographic strip (ICS) were developed for rapid quantitative detection. The optimized ic-ELISA exhibited half-maximal inhibitory concentration (IC50) values of 20.4, 80.1, and 110.4 ng/mL for DBP, DAP, and DEP, respectively, while showing <1% cross-reactivity with other tested phthalate analogues. The ICS enabled visual detection within 15 min, with visual limit of detections (vLODs) of 20, 100, and 200 ng/mL for DBP, DAP, and DEP in edible oils, respectively. By integrating computationally guided hapten design with complementary quantitative and rapid screening formats, this study provides a practical platform for class-selective screening of PAEs in edible oils and a useful strategy for developing group-recognizing antibodies against structurally related small-molecule contaminants.