The invention discloses a preparation method and a Cu<2+> detection application of a
rare earth ratiometric fluorescent probe, and belongs to the technical field of environmental detection. The preparation method of the
luminol-Tb-GMP fluorescent probe is established through the self-
polymerization coordination effect among
luminol, GMP and Tb<3+> by using
luminol and
guanosine monophosphate (GMP)as dual ligands and using a
rare earth ion Tb<3+> as a luminescent center
ion. The luminol-Tb-GMP fluorescent probe combines the dual fluorescent signals of luminol and Tb<3+>, and simultaneously emits dual fluorescent signals of the luminol and Tb<3+> under the same
excitation wavelength. When Cu<2+> exists, the luminol and GMP have a strong coordination effect on the Cu<2+> in order to preventelectrons from being transferred from the amino group of the GMP to Tb<3+>, so
fluorescence quenching of the Tb<3+> is caused, and the
fluorescence intensity of the luminol is unchanged, thereby a Cu<2+> detection method based on the
fluorescence signal ratio of the luminol and Tb<3+> is established. Additionally, the green fluorescence of the Tb<3+> gradually weakens and the blue fluorescence ofthe luminol gradually appears with the increase of the Cu<2+> concentration, so the
visual detection of the Cu<2+> can be achieved. The luminol-Tb-GMP fluorescent probe also can be applied to the sensitive detection of the Cu<2+> in an
environmental water samples and a biological sample.