A Selective Fluorescent Probe for Quantitative Detection of Tiopronin Based on Fluorescence Enhancement

A fluorescent probe ( N -(4-methyl-2-oxo-2 H -chromen-7-yl)-2,4-dinitrobenzenesulfonamide) for selective detection of tiopronin was synthesized and characterized. The probe displays weak fluorescence attributed to electron transfer from the fluorophore to the electron-withdrawing 2,4-dinitrobenzenesulfonyl group. However, upon effective cleavage of the electron-withdrawing 2,4-dinitrobenzenesulfonyl moiety by tiopronin from the weakly fluorescent probe, the fluorescence intensity is significantly enhanced. Under optimal conditions, the fluorescence intensity exhibited a linear correlation with tiopronin concentration within the range of 30 nM to 50 μM. The proposed strategy is characterized by its simplicity, specificity, and sensitivity. The proposed probe was employed for the determination of tiopronin in urine samples and commercial tablets, demonstrating potential applications in disease diagnosis.