水中痕量六价铬离子的激光诱导击穿光谱高灵敏检测

High sensitive detection of trace hexavalent chromium ion in water by laser-induced breakdown spectroscopy

采用旋转电极设计,并利用电沉积技术,使水中痕量的CrO_4^(2-)离子在一个高纯(纯度为99.999%)铝棒表面发生电化学反应并富集,然后利用激光诱导击穿光谱对其进行定量分析.实验研究了电沉积的最佳物理条件,包括沉积电压、沉积时间等.并在沉积电压为10伏,沉积时间为20分钟的条件下制定了六价铬离子的校正曲线并得出其检出限为0.25μg/L.激光诱导击穿光谱结合电沉积技术监测水中六价铬离子的技术具有方法简单、光谱检测灵敏度高、可以区分三价铬和六价铬离子等优点,将在水环境六价铬污染监测方面获得广泛的应用.

With the assistance of electrical-deposition and rotating electrode＇s design, trace CrO4 2- ion in the water was enriched on the surface a high purity （purity equals 99. 999 %） aluminum rod, and quantitatively analyzed with laser-induced breakdown spectroscopy. The optimized parameters of electricaldeposition were experimentally studied, including the deposition voltage and deposition time. Under the experimental condition （ 10 V of deposition voltage and 20 minutes of deposition time ） , a calibration curve for Cr6＋ was obtained. The limit of detection of Cr6＋ under current condition reaches to 0.25 ug/ L （250ppt）. Laser-induced breakdown spectroscopy combined with electrical-deposition is a simple and high sensitive spectral technique for monitoring Cr6＋ ion in water. This technique can also discriminate Cr3＋ and Cr6＋. It will find lots of applications in monitoring of environmental pollution of water due to hexavalent chromium.