【作者】 王忠东；

【导师】 王玉田；

【作者基本信息】 燕山大学 ， 测试计量技术及仪器， 2006， 博士

【摘要】 随着农业科技的发展,农药所带来的污染已经对人、畜、环境生物和水、大气、土壤等环境要素产生了严重的危害,即使农药残留物是痕量的,长期接触也会对人们的生命和健康造成极大的危害。因此,对农药残留物及其代谢物的高灵敏度检测就变得异常重要。传统的农药残留检测方法有薄层色谱法、气相色谱法、高效液相色谱法及生物测定法等。上述方法存在样品前处理过程繁琐、消耗试剂、耗时长等缺点,无法实现快速、绿色检测的需要。光纤荧光检测技术具有检测灵敏度高、取样量少、快速、操作简便,尤其可在恶劣环境下进行远距离在线、连续监测等优点,成为当今环境监测领域的研究热点之一。本文利用荧光光谱分析技术和光纤传感等技术为蔬菜中农药残留物直接检测进行理论与实验研究。研制的系统可以实现对农药残留的无污染、直接快速检测。从荧光测量的基本原理出发,从理论上研究了几种常见农药(氨基甲酸酯类农药、苯甲酰脲类杀虫剂、杀菌剂)的荧光产生的可行性,研究了农药的分子结构与其自然荧光特性关系,实验研究了这几种典型农药的激发光谱、荧光光谱特性以及本底溶剂的荧光光谱特性,研究并选择了它们的最佳激发和荧光发射参数。根据农药的荧光特性,结合光纤传感技术、平场凹面光栅分光和微弱信号检测与处理技术,研制了一种用于监测农药残留物浓度的新型荧光光纤测量系统。系统采用氙灯作为激发光源,配备不同的干涉滤光片实现对于不同农药需要的荧光激发光的选择;设计高效集成化球面光纤探头实现荧光的激发、收集和传输;设计小型平场光谱仪对农药荧光信号实现高分辨率分光;采用高灵敏度的线阵CCD(TCD1208AP)探测荧光信号;通过以微控器和时序发生器ispLSI为控制核心的高速数据采集电路实现信号的采集转换;设计精密的光学耦合器实现光学系统各部件的高效耦合;利用标准光源实现荧光光纤测量系统的光谱波长标定。研究采用小波变换技术进行农药荧光光谱数字滤波、平滑去噪处理;建立基于荧光光谱法进行农药残留定量分析的数学模型;利用线性校正方法实现单组分农药的浓度测量,并结合导数荧光光谱法对两组分农药体系不经前期分离而直接测定了各成分的浓度。更多还原

【Abstract】 With the development of agricultural science and technology, the pollution whichpesticides have brought about has done serious damage to the environment. Thoughpesticide residues are trace components, they can also do great harm to mankind’s livesand health if people have contact with them for a long time. Therefore it becomesexceptional important to detect pesticide residues and their metabolites sensitively.There are some traditional analysis methods for pesticide residues, such as Thin LayerChromatography(TLC), Gas Chromatography(GC), High Efficiency LiquidChromatography(HPLC) and Biological Analysis et al. However, all of them have somedisadvantages including complicated sample pre-processing, consuming more reagentand more time etc. Thus it is impossible to realize fast and green detecting. Becauseoptical fiber fluorescence detecting technology has advantages of high sensitivity, littlesampling,fast detecting and simple operation, especially has advantages of on-line andcontinuous monitoring in the distance under any bad circumstances, it has been one of theresearch hotpots in environment monitoring. In this paper the technology of fluorescencespectrum detection and optical fiber sensing are applied to the study on theory andexperiment of direct detecting pesticide residues in vegetables. With the designedmeasurement system, pesticide residues can be detected fast and directly, as well as nopollution.Starting with the basic principle of fluorescence measurement, the feasibility offluorescence origin of some common pesticides, such as carbamate, benzoylurea andfungicide, is analyzed in theory, and the relationships between the characteristics ofnatural fluorescence and molecular structures are also researched, as well as theexcitation spectra and the fluorescence spectra of these pesticides and the fluorescencespectra of background solvent are studied by experiments, moreover, their best excitationwavelength and emission wavelength are studied and chosen.Based on the fluorescence characteristics of the pesticides, and combined with thetechnologies of optical fiber sensing, light dispersion of flat field grating and weak signaldetecting, a novel optical fiber measurement system for monitoring pesticide residues isdesigned. In this system, a pulsed xenon lamp is accepted as an excitation light sourceand several interference filters are equipped for selecting excitation light for differentpesticides, a high-efficiency sphere optical fiber probe is used to excite, collect andtransmit fluorescence, and a mini flat field spectrometer for fluorescence is designed torealize light dispersion in fine resolution, and a highly sensitive Charge Coupled Device(CCD) is used to detect weak fluorescence signals which are gathered and transformed bythe high speed data-gathering circuits whose control center is MCU and timinggenerator(ispLSI). Simultaneously the precise coupler is designed to realize coupling ofthe optical system efficiently, and the wavelength calibration of the system isimplemented by using a standard light source.Based on wavelet transform technology, digit filtering, smoothness and noise reductionof pesticides fluorescence spectra have been researched, and the mathematic model offluorescence quantitative analysis of pesticide residue has also been set up based onfluorescence spectrum analysis. By linearity calibration principle the concentrationmeasurement of a single component pesticide has been realized. Moreover, combinedwith derivative fluorescence spectra analysis, the concentration of each of thetwo-component pesticides is being mensurated without being separated beforehand.Experiments with standard pesticides and pesticide residues in farm water andvegetables have been made by the new fluorescence optical fiber measurement system forpesticide residues, their fluorescence spectra and the performance indexes of this system,such as the linearity, the minimum detecting limit, recovery and et al, are achievedsuccessfully. By comparing the experiment results of the new system with those of HPLCand GC, the performance of the new system is evaluated, and the rationality andpracticability of this system and the measurement method are validated.更多还原