Smartphone-assisted triple-mode sensing of hydrogen sulfide in food using DMAMC-UCNPs@PEG

Given its dual role in food quality-as both a spoilage indicator and regulated hazardous good, developing an accurate hydrogen sulfide (H 2 S) analysis is critical for food safety and public health. In this work, a novel triple-mode sensor based on fluorescence resonance energy transfer (FRET) between UCNPs@PEG and DMAMC was developed for H 2 S sensitive determination. The synthesized compound DMAMC enable rapidly capture H 2 S with good selectivity via nucleophilic addition, yielding brighter fluorescence, weaker visible absorption, and a paler purple hue. Under optimal conditions, the detection limits for the up-conversion fluorescence, visible adsorption, and colorimetric modes were 0.11 μM, 0.42 μM, and 0.60 μM, respectively. This platform achieved 97.10–107.40 % recoveries in complex matrices (tap water, milk, iceberg lettuce, and pork, RSD <6 %). The triple-mode sensor delivers a 3-min assay, robust anti-interference, and built-in self-calibration. Our work offers considerable potential to strengthen food-safety protocols.