Design of a sustainable light-up flavonol probe for dual-ratiometric fluorescent sensing and visual differentiating ammonia and hydrazine

Ammonia (NH 3 ) and hydrazine (N 2 H 4 ) present potential risks to human health, food and environmental safety. A sustainable flavonol-based probe, quercetin pentaacetate (QPA, weak blue emission 417 nm), was fabricated for dual-ratiometric fluorescent sensing and visual differentiating NH 3 and N 2 H 4 . Excited state intramolecular proton transfer-on products with green (487 nm) and yellow (543 nm) emissions occurred as meeting with NH 3 and N 2 H 4 , respectively, for their different nucleophilicities. Such a promising response offered a great opportunity of QPA to discriminatively detect NH 3 and N 2 H 4 with large Stokes shifts (>122 nm), high sensitivity (limit of detection: 35.4 μM and 0.70 ppm for NH 3 solution and gas; 0.26 μM for N 2 H 4 solution), excellent accuracy (spiked recoveries from 98.6 % to 105 %), and superior selectivity. Importantly, QPA was utilized for monitoring NH 3 vapor in fish spoilage procedures and detecting N 2 H 4 in water samples for food and environmental safety evaluation.