Fluorescence Characteristic of Glutathione-capped Water-soluble CdTe Quantum Dots in Detection of Lead and Mercury Ions

Fluorescence quenching effect of glutathione(GSH)-capped,water soluble CdTe quantum dots (QD′s) was observed when mixed with solution containing Pb(Ⅱ) or Hg(Ⅱ) ion,and the magnitude of decrease in fluorescence intensity was found to keep direct proportionality with the concentration of Pb(Ⅱ) or Hg(Ⅱ) ion present.Based on this fact,a fluorospectrophotometric method for detection of Pb(Ⅱ) or Hg(Ⅱ) ion utilizing the fluorescence quenching effect of GSH capped CdTe QD′s was proposed.By taking concentration of GSH-capped CdTe QD′s at 0.5 μmol·L-1,the magnitude of decrease in fluorescence intensity of 22% (relative %) was obtained in solution containing 10 nmol·L-1 Pb(Ⅱ) ion,and of 20% (relative %) was obtained in solution containing 25 nmol·L-1 of Hg(Ⅱ) ion.Linearity ranges of Pb(Ⅱ) and Hg(Ⅱ) found were 0.01-0.05 μmol·L-1 and 0.025-0.25 μmol·L-1,with detection limits of 0.01 and 0.025 μmol·L-1 respectively.