Blue-emitting copper nanoparticles as a fluorescent probe for detection of cyanide ions

A simple and green method for the determination of cyanide ions (CN^-) has been developed which is based on copper nanoparticles (CuNPs) acting as a fluorescent probe in aqueous solutions. In this study, fluorescent CuNPs have been synthesized in the presence of ascorbic acid which acts both as a reducing and protecting agent. The preparation of CuNPs by this method is very simple, low cost, high yield, and reproducible. The prepared CuNPs have the small average diameter of 10nm and show a blue emission at 440nm. However, upon the addition of CN^- into the CuNPs sensing system, its fluorescence was quenched considerably as a result of the strong interaction between cyanide and copper. Under optimized conditions, a good relationship was observed between the fluorescence quenching of the system and the concentration of CN^- in the range of 0.5-18µmolL^-1 with a detection limit of 0.37µmolL^-1. In addition, the developed sensor has a high selectivity and simple operations. Furthermore, as a cost-effective and selective fluorescent probe, the CuNPs sensor was successfully employed for the detection of CN^- ions in water samples.