Synchronous fluorescence determination of mercury ion with glutathione-capped CdS nanoparticles as a fluorescence probe.

Glutathione (GSH)-capped CdS nanoparticles was successfully synthesized in aqueous solutions at room temperature. Based on the characteristics of synchronous fluorescence spectroscopy (SFS), a simple method with high sensitivity and selectivity was developed for determination of Hg(2+) with GSH-capped CdS nanoparticles as a fluorescence probe. The maximum synchronous fluorescence is located at 335 nm, scanning with excitation and emission wavelengths of 260 and 440 nm (Delta lambda=lambda(em)-lambda(ex)=180 nm), respectively. Under optimal conditions, the quenched fluorescence intensity increased linearly with the concentration of Hg(2+) ranging from 0.15 x 10(-7) to 125 x 10(-7) mol L(-1). The limit of detection was 4.5 x 10(-9) mol L(-1). Compared with several fluorescence methods, the proposed method exhibited several merits in terms of its linear range and the sensitivity. The quenching mechanism was also discussed. Moreover, analytical application of the method was demonstrated by water samples.