适于土壤中农药检测的荧光光纤系统

Fiber-optic fluorescence measuring system suitable for pesticides in soil

提出了一种用于土壤中农药检测的光纤式荧光测量系统。研究了有机物分子发荧光的基本原理，分析了荧光法检测农药的可行性。基于光纤传感技术和荧光技术设计了测量系统，系统以脉冲氙灯为激发光源，以特制的光纤式锥形探头探测荧光，以小型平场光谱仪实现荧光分光，以高速数据采集模块实现荧光信号的采集转换。该系统一次曝光即可获得农药的荧光光谱。利用该系统实现了不同浓度西维因在土壤中的荧光光谱实验，考察了系统的工作曲线和最低检出限。实验结果表明，系统测得的荧光光谱清晰、分辨率高；在0．005～0．1mg／kg范围内荧光强度和浓度基本呈线性关系；系统的最低检出限（LOD）可达0．005mg／kg，相对标准偏差（RSD）≤3％，能够满足土壤中农药检测的需要。

In order to realize on-line measurement for pesticide residua in soil, a fiber-optic fluorescent measuring system was put forward. The foundational principle of organic molecules emitting fluorescence and the feasibility of measuring pesticides by fluorescence method were analyzed. Then, a fiberoptic fluorescent measuring system was established based on the techniques of fiber-optic sensing and fluorescence analysis. In the system, a pulsed xenon lamp was used as an excitation lamp source and a self-made cone-shape fiber-optic probe was used for detecting the fluorescence, a small-sized flat field grating spectrometer for dispersing fluorescence and a high-speed datum-collecting module for collecting and converting the fluorescent signals. The fluorescence spectrum of the pesticide could be obtained with only one exposure of the system. In this way, the fluorescence experiments on carbaryl of different concentrations in soil were carried out and the working curve and the minimum detecting limit of the system were examined. Experimental results show the system can get high-resolution fluorescence spectra with a linear relationship between the fluorescence intensity and the concentration in the range of 0. 005～0. 1 mg/kg. For the Limits of Detection（LOD） of 0. 005 mg/kg and the Relative Standard Deviation（RSD） of ≤3%, the system can surely meet the needs of detecting pesticides in soil.