Selective and sensitive chemosensor for lead ions using fluorescent carbon dots prepared from chocolate by one-step hydrothermal method

Lead is a well-known heavy metal element, and the resulted pollution has absorbed much more attention. It is important and also a great challenge to develop simple and effective methods for sensitive determination of lead ion (Pb2+) from water. Present study described a new chemosensor for the determination of lead ion based on water-soluble fluorescent carbon dots, which were prepared from chocolate using a simple and low-cost one-step hydrothermal method. The fluorescent carbon dots exhibited excitation dependent behavior with the maximum excitation at 280 nm. This novel chemosensor demonstrated high sensitivity and selectivity for the detection of Pb2+ based on the efficient fluorescence quenching effect, which was ascribed to the special chelation between Pb2+ and hydroxyl groups on the surface of carbon dots. The developed chemosensor resulted in a limit of detection as low as 12.7 nM. In addition, the proposed method was validated with five real water samples, and good spiked recoveries were achieved. All these indicated that this new chemosensor had great prospect and would be a good alternative for the routine analysis of lead ion. (C) 2016 Elsevier B.V. All rights reserved.