水中铅元素的激光诱导击穿光谱-激光诱导荧光超灵敏检测

Super Sensitive Detection of Lead in Water by Laser-Induced Breakdown Spectroscopy Combined with Laser-Induced Fluorescence Technique

为了实现对水中有害重金属元素铅的超灵敏快速检测,保证饮用水源的安全,对激光诱导击穿光谱(LIBS)-激光诱导荧光(LIF)联用技术进行研究;采用木片吸水将液体样品分析转换为固体样品分析,消除了采用LIBS技术直接分析水样品时水对原子辐射以及光学收光系统的影响;采用一束可调谐染料激光共振激发激光等离子体中的铅原子,探测其LIF以大幅提高光谱分析的灵敏度;在优化的实验条件下得到水中铅的校正曲线。结果表明,在当前实验条件下铅的检出限可达到3.2×10-9,LIBS-LIF联用技术结合木片吸水法可以直接应用于水环境中痕量铅元素的超灵敏快速检测,从而可监控有害重金属造成的水源污染。

To realize the super sensitive detection of the toxic heavy metal element lead and to ensure safety of drinking water, we study the combined technique of laser-induced breakdown spectroscopy （LIBS） with laser- induced fluorescence （LIF） technique. A wood slice is used to absorb water to convert liquid samples analysis into solid samples analysis, which eliminates the influence of water on atomic emission as well as an optical collecting system in direct analysis of liquid samples with LIBS. Meanwhile, a beam of tunable dye laser is used to excite lead atoms in laser-induced plasma resonantly, and LIF of lead is detected to improve its spectral analysis sensitivity significantly. A calibration curve of lead in water is obtained under optimized experimental conditions. The detection limit of lead in water is determined to be 3.2× 10^-9 under current experimental conditions. It is demonstrated that the LIBS-LIF technique combined with the method of selecting a wood slice as a water absorber can be applied to realize direct, fast, and super sensitive detection of trace lead in water, thus the water pollution due to toxic heavy metals can be monitored.