Portable fluorogenic probe for monitoring of volatile amine vapour and food spoilage

There are urgent needs of volatile amine gas sensors with high-performance in food quality control, disease monitoring and environmental pollution. Thin-film fluorescent probe is suitable for amine vapour sensing due to its high sensitivity, high selectivity, and no polluting analyte. Herein, a novel fluorescent probe based on indacenodithiophene structure with π conjugated system was designed and synthesized. The experimental results show that the films prepared by this material exhibit rapid and distinct fluorescence quenching after being exposed to saturated vapours of primary amine, secondary amine and tertiary amine represented by n-propylamine, diethylamine and trimethylamine, respectively. The quenching of fluorescence is 84%, 87% and 96%, respectively, within 10 s. The detection mechanism of probe for primary amine is based on specific chemical reaction, while the detection mechanism for secondary amine and tertiary amine is intramolecular charge transfer. Further experiments show that the detection limit of the fluorescent probe for trimethylamine, an important marker of food spoilage, could reach 4.610 ppt. On-site detection based on spoilage of small yellow croaker suggests the material possesses the potential for food freshness detection. This simple fluorogenic probe is an original approach to simplify real-time visual monitoring of volatile amine vapour.