Copper/Zirconium MOF Electrochemical Sensing Platform for High Sensitivity Analysis of Bisphenol S in Real Samples

Abstract 4,4′-sulfonyldiphenol (Bisphenol S, BPS) is used as a substitute for bisphenol A (BPA) in industrial plastic and epoxy resin production. However, it still retains estrogenic activity similar to BPA, with a longer biological half-life and stronger skin permeability than BPA, can lead to toxic pollution, and bring various health risks to humans. Consequently, it is crucial to develop a simple, specific, and sensitive detection method for the quantification of BPS. In this work, a copper/zirconium MOF bimetallic organic framework-based composite (CuZr-MOF/MXene/CNTs, BMC) was prepared through a hydrothermal method for sensitive electrochemical determination of BPS. The distribution of Cu-MOF and Zr-MOF around the MXene formed a tight bond, making the obtained BMC a stable structure, while the incorporation of MXene and carbon nanotubes (CNTs) significantly improved its electrical conductivity. Under optimized conditions, the sensor exhibited a well-defined linear dependence between the peak current and BPS concentration in the range from 0.2 to 50 μM, with a low limit of detection (LOD) of 0.0396 μM. The modified BMC sensor was employed to quantify trace levels of BPS in real samples and achieved good recovery rates, demonstrating its practical applicability in real samples. Selectivity tests demonstrated satisfactory tolerance toward interfering metal ions (K+, Na+, and Mg2+) and compounds with similar structures (glucose, ascorbic acid, glycine, hydroquinone, BPA, and phenol). It also demonstrated commendable reproducibility and appropriate performance in three batches of production with a relative standard deviation (RSD) of 0.409%. The sensor can also show good stability for over 35 days. This work provides a new technical strategy for the sensitive detection of toxic BPS in real samples by coupling the active sites of bimetallic MOFs and the high conductivity of CNTs and MXene.