Phthalate esters are widely used as a plasticizer in many consumer products. Dibutyl phthalate (DBP) is one of the most common phthalates and it toxic to humans, especially affecting reproduction and development. The contamination of water by DBP must be controlled. The maximum residue limits (MRLs) of DBP in water is about 0.5 ng/mL, but this level is very often exceeded in real water samples. Simple and fast methods for detection of DBP at the level of tenfold excess of MRL are needed. The present study aimed to develop a fluorescence polarization immunoassay (FPIA) based on the use of monoclonal antibodies generated against DBP. Fluorescein-labeled tracers of the carboxyl derivative of DBP were synthesized with various fluorescein dyes. The advantages of using 5-aminomethylfluorescein as a dye are shown. The analysis conditions for FPIA of DBP were optimized, which made it possible to determine DBP in 0.5 ml of water sample at a level of 5 ng/ml. Samples of wastewater from pharmaceutical enterprises were analyzed and it was found that, along with uncontaminated samples, there were samples with a concentration of up to 10 ng/ml of DBP.

Conflicts of Interest:
The authors declare that they have no conflict of interest in the publication of this article. The authors have no conflicts of interest to report in this work. Abstract was not submitted elsewhere and published here firstly.

Funding:
This study was financially supported by the Russian Science Foundation (grant no. 21-14-00306).