Fluorescence Quenching of CdS Quantum Dots and Its Application to Determination of Copper and Nickel Contamination in Well and Dam Water

Abstract

A sensitive and simple method based on the fluorescence quenching CdS quantum dots (QDs) was reported for the determination of copper(Cu2+) and nickel (Ni2+) in water samples. Water-soluble and biocompatible thioglycolic acid- capped CdSQDs was synthesized by one step process, then characterized by fluorescence, absorption spectroscopy and transmission electron microscopy (TEM). The fluorescence intensity of synthesized QDsremarkably decreased in the presence of Cu2+ and Ni2+ ions. The emission of CdSQDs had a linear decreasing relationship with Cu2+ and Ni2+ concentration in the range of 0.6 to 200 and 1 to 250 ng mL-1 with detection limits of 0.15 and 0.4 ng mL-1, respectively. Other potentially interfering ions such as iron, sodium, potassium, calcium, and magnesium ions did not affect the luminescence. The method showed good sensitivity and was satisfactorily applied to the determination of Cu2+ and Ni2+ contamination in real water samples, obtained from Nahand dam, Karkaj and Azarshahr well, tab and mineral waters.