Colorimetric detection of phthalate esters based on peroxidase–like activity of Fe-MOFs

Accurate detection of phthalic acid esters (PAEs) in food samples is critically important for food safety monitoring due to their endocrine-disrupting effects. A colorimetric (CL) sensing platform was developed, which shows universal response to all PAEs analytes. In the sensing system, Fe-MOFs with peroxidase-like (POD-like) activity catalyze H 2 O 2 to generate reactive oxygen species (ROS), which oxidize colorless 3,3′,5,5′-tetramethylbenzidine (TMB) into blue oxidation product (oxTMB). However, after the addition of PAEs, it will compete with TMB for active substances, resulting in a decrease in the generated oxTMB. Therefore, with the increase of PAEs concentration, the intensity of UV absorption peak attributed to oxTMB decreased. Taking dibutyl phthalate (DBP) as an example, the linear equation between absorption intensity ( A 652 ) and target concentration (1.0 × 10 −9 –5.0 × 10 −5  mol/L) was established. The correlation coefficient ( R 2 ) was 0.996, and the limit of detection (LOD) was 2.7 × 10 −10  mol/L. The signal response evaluation of multiple target PAEs was carried out separately. The CL sensing platform constructed using Fe-MOFs has been proved to be a reliable sensing system for the detection of DBP in real samples and yielded satisfactory recovery results. The successful application of this method for the detection of DBP in pakchoi, cherry tomato and fruit cucumber samples showed that it has the potential to detect PAEs in complex samples.