Development of a highly sensitive biotin–streptavidin enzyme-linked immunosorbent assay for detecting diethyl phthalate based on a specific polyclonal antibody

An indirect competitive biotin–streptavidin enzyme-linked immunosorbent assay (BA-ELISA) has been established for the determination of diethyl phthalate (DEP) in wine samples. A highly sensitive and specific polyclonal antibody (pAb-DEP) targeting DEP was prepared. Under optimized conditions, good linearity was achieved within a range of 0.021–9.512 μg·L⁻¹. The limit of detection (IC₁₀) was 0.0079 μg·L⁻¹ and the median inhibitory concentration (IC₅₀) was 0.443 μg·L⁻¹. Besides, the BA-ELISA was highly selective, with low cross-reactivity values with DEP analogs (below 5%). Finally, the concentrations of DEP in wine samples ranged from 5.93 μg·L⁻¹ to 59.15 μg·L⁻¹ by BA-ELISA. Satisfactory recoveries (89.19–112.33%) and variation coefficient values (5.81–9.43%) were successfully obtained. The consistency between the results of BA-ELISA and gas chromatography–mass spectrometry (GC–MS) was 97.48%, which further confirmed that the proposed BA-ELISA immunoassay is reliable, rapid, sensitive, and accurate for monitoring DEP in wine samples.