Simultaneous spectrofluorimetric determination of the rare earths with calcein

The reactivity of the fluorescent reagent calcein with the trivalent cation s of the rare earths has been spectrofluorimetrically studied in aqueous so lution. Optimum excitation and emission wavelengths were 492-497 and 519-52 2 nm, respectively. Optimum pH was in the range 6.0-9.2. The stoichiometry of the complexes was 1:1. A direct, rapid and sensitive method for the dete rmination of rare earth mixtures has been proposed with a detection limit o f 4.49 x 10(-8) M and a coefficient of variation of 0.82%. (C) 1999 Elsevie r Science B.V. All rights reserved.