基于荧光机理的土壤农药浓度光纤检测系统

The Fiber-Optic Measurement System for Pesticides' Concentration in Soil Based on Fluorescent Mechanism

根据有机物分子受激发荧光的基本原理,分析了荧光法检测农药的可行性.基于光纤传感技术、荧光分析技术提出了一种能够检测土壤中有机农药浓度的光纤式荧光测量系统.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的西维因在土壤中荧光光谱实验,考察了系统的工作曲线和最低检测限.实验结果表明,系统能够获取分辨率较高的荧光光谱;在0.005 mg/kg^0.1 mg/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0.005 mg/kg,相对标准偏差(RSD)≤3%.该系统能够满足土壤中农药浓度检测的需要.

The feasibility of measuring pesticides by fluorescence method is analyzed on the foundational principle that molecules of organic substance can emit fluorescence when excited by rays. A fiber-optic fluorescent measuring system, which can be used for detecting the organic pesticides＇ concentration in soil, is put forward based on the technique of fiber-optic sensing and fluorescence analysis. In the sys tem, a pulsed xenon lamp is used as an excitation lamp source, a self-made cone-shape fiber-optic probe for detecting the fluorescence, a small-sized flat field grating spectrometer for dispersing fluorescence, a high-speed data-gathering module for gathering and converting the fluorescent signals. The fluorescence＇s spectrum of the pesticide is obtained with only one exposure of the system. In this way, the fluorescence experiments on carbaryl of different concentration in soil were done and the working curve and the minimum detecting limit of the system were examined. The results show the system can get high-resolution fluorescence spectra, and has a linear relationship between the fluorescence intensity and the concentration in the range of 0. 005 mg/kg-0. 1 mg/kg, and the minimum detecting density （LOD） is 0. 005 mg/kg, the relative standard deviation （RSD） is ≤3 %. Consequently, the system can surely meet the need of detecting pesticides＇ concentration in soil.