Determination of Eu(III) based on fluorescence and cofluorescence enhancement of Eu(III)-Tb(III)-tetracycline-citrate system

Abstract

A new sensitized cofluorescence system has been developed for the determination of Eu(III) based on its complex formation with tetracycline (TC) in the presence of citrate and Tb(III). Eu(III) forms complex with tetracycline in alkaline condition which emits intrinsic fluorescence of Eu(III) when excited. The fluorescence intensity of Eu(III)TC is enhanced about 5 times when citrate and Tb(III) are introduced. The factors that influence the fluorescence intensity of the system have been studied in detail. Under optimum conditions, the relative fluorescence intensity is linear in over the range 6.0×10⁻⁹ to 4.0×10⁻⁶ M of Eu(III). The detection limit has been found to be 1.4×10⁻⁹ M of Eu(III). The method has been used for the determination of Eu in two rare earth samples with relative error 4.5% and -1.8%, and RSD 2.6% and 2.1%, respectively.