Detection of europium(III) and samarium(III) by chelation and laser-excited time-resolved fluorimetry

Among the luminophores potentially usable as markers for biological molecules (e.g., antibodies and nucleic acids) the lanthanide cations (Ln^3su+) are the most efficient in terms of both signal selectivity and analytical sensitivity. These ions, chelated by certain β-diketones, in particular 2- naphthoyltrifiuoroacetone, can be detected at concentrations down to ca. 10^?18 mol in 300 μl by means of a pulsed excitation source (e.g., a laser) coupled to a time-resolved luminescence detection system. Such a device permits the total rejection of the optical background. The simultaneous quantitation of Eu³⁺ and Sm³⁺ is evaluated, and their use for possible simultaneous double labelling of biomolecules is predicted.