Development of a Highly Specific Fluorescence Immunoassay for Detection of Diisobutyl Phthalate in Edible Oil Samples

The diisobutyl phthalate (DiBP) hapten containing an amino group was synthesized successfully, and the polyclonal antibody against 4-amino phthalate-bovine serum albumin (BSA) was developed. On the basis of the polyclonal antibody, a rapid and sensitive indirect competitive fluorescence immunoassay (icFIA) has been established to detect DiBP in edible oil samples for the first time. Under the optimized conditions, the quantitative working range of the icFIA was from 10.47 to 357.06 ng/mL (R(2) = 0.991), exhibiting a detection limit of 5.82 ng/mL. In this assay, the specific results showed that other similar phthalates did not significantly interfere with the analysis, with the cross-reactivity less than 1.5%, except for that of DiBAP. Thereafter, DiBP contamination in edible oil samples was detected by icFIA, with the recovery being from 79 to 103%. Furthermore, the reliability of icFIA was validated by gas chromatography-mass spectrometry (GC-MS). Therefore, the developed icFIA is suitable for monitoring DiBP in some edible oil samples.