Ultrasensitive mercury(II) ion detection by europium(III)-doped cadmium sulfide composite nanoparticles

With the biomolecule glutathione (GSH) as a capping ligand Eu3+-doped cadmium sulfide composite nanoparticles were successfully synthesized through a straightforward one-pot process An efficient fluorescence energy transfer system with CdS nanoparticles as energy donor and Eu3+ ions as energy accepter was developed As a result of specific interaction the fluorescence intensity of Eu3+-doped (dS nanoparticles is obviously reduced in the presence of Hg2+ Moreover the long fluorescent lifetime and large Stoke s shift of europium complex permit sensitive fluorescence detection Under the optimal conditions the fluorescence intensity of Eu3+ at 614 nm decreased linearly with the concentration of Hg2+ ranging from 10 nmol L-1 to 1500 nmol L-1 the limit of detection for Hg2+ was 0 25 nmol L-1 In addition to high stability and reproducibility the composite nanoparticles show a unique selectivity towards Hg2+ ion with respect to common coexisting cations Moreover the developed method was applied to the detection of trace Hg2+ in aqueous solutions The probable mechanism of reaction between Eu3+-doped CdS composite nanoparticles and Hg2+ was also discussed (C) 2010 Elsevier B V All rights reserved