Abstract: In this study, a fluorescence sensor based on carbon dots was constructed for sensitive visual detection of heme chloride (HC) in foods. The new double-emission yellow-emitting carbon dots (y-CDs), synthesized by a one-step hydrothermal method using L-glutamic acid and o-phenylenediamine (OPD) as precursors, had high fluorescence stability at pH 3–12, 20–60 ℃ and ultraviolet (UV) excitation wavelength 360 nm. The fluorescence emission intensity of y-CDs at 430 and 530 nm was simultaneously quenched by HC. A ratiometric fluorescence method and a visual colorimetric method were developed for the determination of HC in meat products. The experimental results showed that the ratiometric fluorescence sensor exhibited excellent linearity in the concentration range of HC from 5 to 100 μmol/L for both ratiometric fluorescence and visual colorimetric methods, with limits of detection (LOD) of 2.3 and 0.002 μmol/L, respectively. The recoveries of the two methods were in the range of 99.55%–102.20% and 99.8%–100.40% for actual samples, with relative standard deviations of 0.94%–3.17% and 0.2%–1.5%, respectively. The new methods are rapid, simple, sensitive, reliable, and suitable for visual quantitative detection of HC in foods, and the dual-emission fluorescent carbon dots have good prospects for future application in fluorescence sensing and colorimetric detection.

Key words: carbon dots; fluorescence detection; visual detection; heme chloride