LAUSR

A novel device is designed for rapid detection of trace Cu2+ residues in paddy water using dual-wavelength quantum dot fluorescence probe. It includes three operation procedures: synthesis of dual-wavelength quantum dot, fluorescence excitation and acquisition of weak signal and signal conditioning. Based on the quenching principle of Cu2+ on quantum dot fluorescence, dual-wavelength quantum dot fluorescent probe can get lower limitation of detection. In addition, to improve the accuracy of testing results, two-channel detection was developed for avoiding interference. Experiment results demonstrate that the limitation for detection of trace Cu2+ in paddy water is 1.4 nM. The relationship between the Cu2+ concentration (x) and the ratio variation of dual wavelength (y) is y = 2.15 × exp(x/5.862) − 1.154 with the coefficient of determination (R2) of 0.997 and the detection time of 4 min. Meanwhile, compared to other heavy metal ions, nutrient and organic compounds, the presented detector is of good selectivity for Cu2+ in paddy water. The repetitive detection experiments show that the developed device has high repeatability with relative standard deviation of 0.14%. The device can be used for quick and accurate detection of trace Cu2+ residues in paddy water with some specific advantages of high sensitivity, excellent selectivity and high repeatability.