Cu(II) detection by a fluorometric probe based on thiazoline-amidoquinoline derivative and its application to water and food samples.

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Citation abstract

Two novel fluorescent probes for Cu 2+ detection have been developed based on thiazoline-quinoline conjugates bearing a 4-ethynyl-N,N-dimethylaniline unit (QT1 and QT2). QT2 exhibits instantaneous fluorescence quenching of Cu 2+ with an emissive change from bright orange to arctic blue under UV light irradiation (365 nm). The plots of I 0 /I against Cu 2+ concentrations show a good linear relationship that ranges from 0 to 50 µM with a coefficient of determination (R 2 ) = 0.9906 and a limit of detection (LOD) of 76 nM, which is considered low (4.84 ppb). A 1:1 complexation between QT2 and Cu 2+ was confirmed by UV-Vis titration, ESI-MS, and SC-XRD. The QT2·Cu 2+ complex was dissociated by the addition of EDTA. The fluorescence quenching mechanism involves the ligand-to-metal charge transfer (LMCT) of a paramagnetic Cu 2+ complex. The QT2 probe on a paper-based strip was used to determine the amount of Cu 2+ in water and food samples (shiitake mushrooms and oysters).