Determination of Trace Nickel(ΙΙ) Using a Kinetic Fluorescence Method with a Morin-Hydrogen Peroxide System

Nickel (Ni[Ⅱ]) was used to catalyze the hydrogen peroxide oxidation of morin to weaken its fluorescence. In Na2B4O7-NaOH buffer solution at pH 10.10, Ni(Ⅱ) has an obvious catalytic effect on the oxidation of morin by H2O2 solution. At the maximum excitation and emission wavelengths (λex = 440 nm and λem = 530 nm), the fluorescence intensity of the system is linearly correlated with the concentration of Ni(II) within a certain range. The linear equation is ΔF = 11463ρ (μg/mL) − 34.70, and the R2 = 0.9992. The linear range is 1.6 × 10-2 − 9.6 × 10-2 μg/mL, and the detection limit was 2.9 × 10-4 μg/mL. Finally, the samples of tap water, Yellow River water and tea were analyzed, with the recoveries being 99.6%, 107.3%, and 104.6%, respectively. This method is suitable for the determination of trace Ni(II) in water samples.