A New Fluorescent Switch for Determination of Pb2+ Based on Modified CdTe Quantum Dots

CdTe quantum dots (QDs) modified with 4-aminoantipyrine shrink 2,5-dihydroxylbenzadehyde Schiff base were synthesized and characterized using infrared spectrum (FTIR), ultraviolet-visible spectrum (UV-vis), photoluminescence (PL), TEM and thermal gravimetric analysis (TGA). The as-prepared fluorescent switch was subjected to the determination of Pb2+ by the fluorescence resonance energy transfer (FRET). There were two successive linear relationships between the fluorescent intensity and Pb2+ concentration, in the concentration range of 0.01–100 μmol/L and 100–10000 μmol/L with r = 0.9994 and r = 0.9996, respectively, and accompanying with 3.0 nmol/L limit of detection. The proposed method was successfully applied to detect Pb2+ in industrial sewage samples and the results showed that the relative standard deviation was less than 4.1%, with a recovery of 96.7–102%.