Fiber-optic measurement system for pesticides residua based on fluorescence mechanism

A measurement system is introduced using the technologies of fiber-optic sensing, dispersion of grating and multi-channel image sensing based on fluorescence mechanism of pesticides. The system adopts a pulsed xenon lamp as an excitation light source, chooses optical fibers to transmit and detect fluorescence, implements dispersion of fluorescence with a small-sized flat field grating spectrometer and conducts data gathering and conversion with a high speed signal processing module. A full fluorescence spectrum of pesticides within a single exposure can be gotten. Moreover, it is used to conduct the measurement of fluorescence characteristics of carbaryl and carbofuran. The results show that the pesticides can emit fluorescence of 340-750 nm as excited by ultraviolet (UV) light of 319 nm,and the system has a good linear relationship in the range of 0.003-0.1 mg/L and the minimum detecting limit is 0.003 mg/L. At the same time, the instrument is also be applied to detect concentration of the trace pesticides in Chinese cabbages,the recovery may be closed to 100%.