Determination of Trace Amount of Co2+ Based on the Fluorescence Quenching Effect of CdS Quantum Dots

Mono-dispersed CdS-quantum dots (CdS-QDs) were prepared using thiohydracrylic acid as stabilizer. It was found that the fluorescence of the CdS-QDs was quenched intensely by Co2+ in a reaction medium at pH 7, and that the magnitude of quenching of fluorescence intensity (ΔF/F) was controlled by the Stern-Volmer equation when the concentration of Co2+ was in the range of 1.0×10-5-2.5×10-4mol·L-1, value of detection limit (3s) found was 1.3×10-6mol·L-1. Based on these facts, a fluorometric method for determination of trace amounts of Co2+ was proposed. Values of recovery found by standard addition method were in the range of 93.8%-105%, and values of RSD′s (n=6) found were less than 4.0%.