| As important input material in agricultural production, pesticides play an irreplaceable role in promoting agricultural development, satisfying people's demand for agricultural products.But the pesticide itself is a class of toxic chemical substance, the pollution due to irrational use of pesticides has done serious damage to human healthy and ecological environment. Therefore, we must strengthen the detection of pesticide residue and their metabolites.There are some disadvantages in traditional analysis methods for pesticide residues, such as complicated sample pre-processing and consuming more reagents. Whereas fluorescence analysis method has an advantage of high sensitivity, strong selectivity and less reagent in the detection of concentration and composition analysis, it shows superiority especially in the detection of pesticide residues. This paper intends to develop a fluorescence optical fiber measurement system which is used in the analysis of pesticide residue, combining the technology of fluorescence spectrum detection and optical fiber sensing, to achieve the direct detection rapidly.Starting with the basic principle of fluorescence analysis method, the relationships between molecular structure of some common pesticides (benzoylurea and carbamate) and their fluorescent characteristics are researched, as well as the excitation spectrums and the fluorescence spectrums of these pesticides are studied through experiments, what's more, their optimal excitation wavelength and fluorescence spectral range are choosen.According to the fluorescent characteristics of pesticides, a fluorescence optical fiber measurement system based Charge-Coupled-Device for detecting pesticide residue is designed. In this system, a short-arc pulsed xenon lamp is choosen as the excitation light source, several interference filters are equipped to meet the need of different pesticides for selecting excitation light; a Y-type optical fiber bundles and spherical optical fiber probe are used for collection and transmission of the excitation light and fluorescence signal; a linear array CCD (RL2048DKQ) with high speed and low power is choosen as photoelectric detector, the corresponding filter and amplifying circuits are also designed; AD16-2K high-speed data acquisition card is accepted to achieve collection and conversion of the signal; the computer software for further processing of the data is designed moreover.The work curves of these pestcides have been determined by the new system, as well as some performance indexes such as accuracy, precision and so on. By comparing the experimental results of this system with those of other standard methods, the rationality and feasibility of the detection method are validated. |
