Abstract:

A new protocol for the determination of copper was developed based on the fluorescence quenching of carboxymethyl cellulose(CMC) coated CdS quantum dots(QDs), which were synthesized in aqueous solution using environmental benign carboxymethyl cellulose as stabilizer. The method has a relatively high selectivity, and no obvious interference on the determination of copper from other coexisting metal ions is observed except Co2+ and Hg2+ ions. Some influencing factors, including the buffer system, pH of the solution, concentration of QDs, reacting time and the temperature of reaction have also been investigated to obtain the optimal conditions for copper determination. When the concentration of QDs was 2×10-4 mol/L, the concentration of KH2PO4-Na2HPO4 is 0.033 mol/L at pH=5.6, the relative fluorescence intensity of QDs was linearly proportional to copper(Ⅱ) ion concentration in the range from 5×10-8 to 2×10-5 mol/L. The linear equation was F0/F=1.015 0+100 791.6c, and the detection limit was 8×10-9 mol/L. This method is simple and rapid. Compared with the methods reported using QDs as fluorescence probes, this method has a higher selectivity and a wider linear range. The proposed method has been applied to the determination of trace copper in water and human hair with satisfactory results.

Key words: CdS quantum dots, fluorescence quenching, determination, copper ion, water, human hair