Search

The amine vapour produced by microorganisms is an important indicator of food spoilage. Amines are also ubiquitous in the chemical industry. The development of molecule-based ion sensors has been a pivotal issue that is currently receiving considerable attention. In this work, a new pyrylium salt-based fluorescent probe MTPY has been developed as a rapid, highly sensitive, and selective sensor for methylamine vapour. MTPY exhibits an obvious fluorescence response from yellow to cyan towards CH3NH2 vapour. The calibration curve of titration analysis shows a linear relationship of the fluorescence intensity at 514 nm versus the methylamine concentration in the range of 0.1–2 ppm. In addition to the linearity (R2 = 0.974) and short response time with a low detection limit (2.6 ppt, 8.4 × 10−8 M), the sensing mechanism was traced using mass spectrometry. [ABSTRACT FROM AUTHOR]

A highly sensitive and selective colorimetric and NIR fluorescent probe NRB was reported with a LOD of 50 and 16 ppt. The probe can be used to trace food spoilage. [Display omitted] • A dual-channel colorimetric and NIR fluorescent probe NRB was described. • NRB could detect various amines effectively both in solution and in vapor. • NRB is sensitive to amines (LOD for MeNH 2 is 17 and 50 ppt via fluorescence spectrometry and naked eyes respectively). • NRB could serve as a portable sensor for monitoring food freshness. In this work, we reported a chromogenic and near infrared (NIR) region fluorogenic dual-channel probe NRB, which could visually detect gaseous amines with high sensitivity (eg. 50 and 17 ppt for methylamine (MeNH 2) via naked eyes and fluorescence spectrometer respectively). It exhibited a wide fluorescent emission band extending to the NIR region with a peak at 615 nm when stimulated by the MeNH 2 solution. The plausible sensing mechanism was proved by mass spectrometry, where the reaction process was based on a nucleophilic substitution between the probe and amines rather than the ester group hydrolysis. Furthermore, NRB was successfully applied to monitor the food freshness (seafood and meat food), because of its low cytotoxicity and excellent photophysical properties. It was worth mentioning that real time monitoring for food quality can be realized visually by using a 365 nm UV lamp. In addition, the probe was stable during the quality guarantee period for perishable packaged food. It was believed that the applied experiments have demonstrated the value of this probe in the practical applications for food safety. [ABSTRACT FROM AUTHOR]