Ultratrace Determination of Selected Lanthanides by Luminescence Enhancement

Abstract

The luminescence intensity of trivalent lanthanides, especially terbium(III) and europium(III), is shown to be enhanced by coordination with the ligand 2,6-pyridinedicarboxylic acid (DPA). Further enhancement can be obtained by forming a columinescent complex aggregate with ions such as gadolinium(III), terbium(III), lanthanum(III), or yttrium(III), where the Y(III) complex shows the greatest enhancement. A surfactant, sodium dodecyl sulfate (SDS), can be added to the solution to enhance the luminescence intensity of many lanthanide-ligand complexes by segregating the complex from quenchers. In this study, SDS has little effect on the limit of detection, but it does act to extend the linear dynamic range to include higher concentrations. The combination of columinescent complex with surfactant resulted in decreased luminescence intensity coupled with an increase in the background due to the light scattered by the surfactant micelles. A mechanism for the enhancement of the lanthanide luminescent intensity by energy transfer has been described by Xu et al. This study differs in that a lanthanide ion excitation band represents the most efficient excitation path and not a ligand excitation band. The complexes examined in this study have advantages over those used in prior studies since they do not require surfactants to achieve low limits of detection (100 parts per quadrillion, ppq, for Eu(DPA)(3)(3)(-) and 60 ppq for Tb(DPA)(3)(3)(-)), and they exhibit longer linear dynamic ranges (from 4 to 6 decades) than other columinescent systems.

Sensitization of uranium fluorescence using 2,6-pyridinedicarboxylic acid: Application for the determination of uranium in the presence of lanthanides

“…Furthermore, as mentioned earlier, PDA also serves as an efficient ligand for sensitizing and enhancing the fluorescence of Eu 3+ , Tb 3+ and Dy 3+ [27,28,[44][45][46]. The fluorescence intensities of these rare earths in aqueous medium were enhanced by more than two orders of magnitude when these lanthanides were complexed with PDA.…”

“…A promising alternative that provides both sensitivity and selectivity is fluorescence spectroscopy; a technique that has greatly contributed to the ultratrace determination of fluorescent materials. There are a number of reports in the literature demonstrating the use of spectrofluorimetry for the simultaneous determination of rare earths [19][20][21][22][23][24][25][26][27][28][29]. In a number of these reports, ligand sensitized fluorescence (LSF) and cofluorescence have been used for the determination of lanthanides.…”

Spectrofluorimetric Determination of Trace Amounts of Europium(III) Ion with Lutetium(III)-Sparfloxacin-Sodium Dodecyl Sulfate Luminescence Enhancement System

“…8 Another efficient way for enhancing the luminescence of lanthanide ions is called the co-luminescence effect. 9,10 According to this method, the addition of certain lanthanide ions, such as La 3+ , Ga 3+ , Tb 3+ , Lu 3+ and Y 3+ , can considerably enhance the luminescence intensity of the chelates of Eu 3+ , Sm 3+ , Tb 3+ in solution. This type of luminescence enhancement is actually an intrinsic luminescence phenomenon that occurs through an intermolecular energy-transfer process.…”

A Path to Soluble Molecularly Imprinted Polymers

“…This process is more efficient than direct absorption of light by the lanthanide due to the poor absorptivities of the lanthanides (formally atomically forbidden absorbance for the intra-configurational f→f transition). A large number of organic ligands have been used to enhance lanthanide luminescence intensity [21]. When making an imprinted polymer sensor, the ligands must be chosen with sufficient affinity for the lanthanide, so as to coordinatively bind the ion in the polymer as well as provide intense luminescence.…”