Ethyl (Z)-2-cyano-4-oxo-3,4-diphenylbut-2-enoate: A novel fluorescent probe for selective detection of vanillin in food samples

Vanillin is widely used in food and industrial applications, but excessive intake of vanillin can pose health risks. Therefore, the development of novel detection strategies with high sensitivity and selectivity is essential for the accurate identification of vanillin. Ethyl ( Z )-2-cyano-4-oxo-3,4-diphenylbut-2-enoate (ECOD), a novel fluorescent probe, was synthesized by an elimination reaction using ethyl cyanoacetate, benzil, and aqueous ammonia as raw materials. The probe exhibited maximum fluorescence excitation and emission wavelengths at 300 and 340 nm, respectively, with a quantum yield of 22.6%. ECOD was found to have high selectivity and sensitivity for the detection of vanillin. This was attributed to ECOD binding to vanillin, which induced conformational changes and triggered intermolecular charge transfer (ICT), ultimately resulting in fluorescence quenching. Therefore, a fluorescence-based method was established for the quantification of vanillin in biscuits, candy, and milk sauce. The linear detection range was 1.0–100 µM and the detection limit was 0.33 µM. The recoveries ranged from 93.2% to 113%, with an RSD ranging from 2.8% to 10%. These results indicated that ECOD had significant application potential in food analysis, suggesting that the fluorescence method based on ECOD could provide a novel approach for rapid vanillin determination in complex food matrices.