水体重金属电解液阴极脉冲放电光谱低检出限检测研究

电解液阴极放电光谱是近年来出现的一种在线检测水体金属元素的新方法。该技术具有开放大气环境工作，进样简便，体积小，运行费用低，可同时检测多种金属元素等显著特征。但该方法对重金属元素的检出限偏高，限制了对重金属的检测能力。为此，本项目拟开展脉冲电源维持的大气压电解液阴极放电光谱技术研究：采用高压脉冲电源驱动，提高等离子体的电子激发温度，促进重金属元素的原子化和被激发，结合电极结构优化和气体吹动等措施，增强等离子体稳定性、消除背景光谱干扰，实现水体重金属的低检出限检测。本项目将研究高压脉冲放电对重金属原子辐射和等离子体的电子激发温度、电子密度等参数的影响；探索重金属离子在溶液-等离子体界面上的迁移机理和在等离子体区内的复合激发机理，揭示电解液阴极放电等离子体的基本特性，获得提高光谱辐射强度、信噪比和检测灵敏度的方法。研究结果将为开发微型、低成本的水体重金属在线检测设备提供重要实验依据和仪器参数。

Electrolyte cathode atmospheric pressure glow discharge-atomic emission spectrometry (ELCAD-AES) is a new technique to on-line detect metal elements in aqueous solutions in recent years. It has many notable advantages, such as working at atmospheric pressure, simple injection, small size, low operating costs, and detection multi-metal-elements at the same time. However, this technique operates high detection limit for heavy metal elements, which limits its detection capability. Therefore, in the present project, we intend to carry on atmospheric pressure electrolyte cathode discharge spectroscopy sustained by a pulse power supply: the pulse power supply will be employed to generate plasma in order to improve electron excitation temperature of plasma, which will promote atomization and stimulated efficiency of heavy metal elements, and then enhance the stability of plasma and eliminate the background spectral interference by optimizing electrode structure and gas blowing. The detection limit of ELCAD-AES for heavy metals in aqueous solutions will become lower by these improvements. We will study the effects of high voltage pulsed discharge on the atomic radiation intensities of heavy metals and plasma parameters (such as electron excitation temperature, electron density, etc.), and explore the migration mechanisms of heavy metal ions in solution-plasma interface as well as the recombination and excitation mechanisms in the plasma region, and reveal the basic properties of the electrode cathode discharge plasma, and obtain the methods to improve spectral radiation intensity, signal to noise ratio and detection sensitivity. The research results will provide important experimental references and instrument parameters for developing miniature, low-cost heavy metals online detection equipment in aqueous solutions.