Studies of the effect of halide ions on the fluorescence of quinine sulfate

The effect of halide ions (Cl-, Br- and I-) on the fluorescence of quinine sulfate in dilute sulfuric acid solution was studied by fluorescence spectra, ultraviolet-visible (UV-visible) absorption spectra and fluorescence decay technique. The results exhibited that halide ions with heavier atomic mass could significantly reduce the fluorescence intensity of quinine sulfate, as a result, the order of fluorescence quenching caused by halide ions is Cl- < Br- < I-. Therefore, halide ions with high concentration could seriously quench the fluorescence of quinine sulfate. The UV-visible absorption spectra and fluorescence decay technique revealed that the fluorescence quenching of quinine sulfate caused by halide ions was attributed to dynamic quenching, static quenching process, self-quenching fluorescence effect and electronic transfer.