为了建立一套高灵敏和低成本的液体样品金属元素检测分析方法, 设计制造了一套超声波雾化辅助电火花击穿光谱(UN-SIBS)的实验系统。 利用超声波雾化装置将液体样品转化为密集小液滴组成的气溶胶, 并使用高压放电线圈和铜电极击穿气溶胶样品诱导等离子体, 通过采集分析光谱信号实现对样品金属成分的分析。 实验研究了该方法的发射光谱谱线特性, 对等离子体的电子温度和密度等物理特性参数进行了计算分析。 针对含有不同浓度重金属铅(Pb)元素的样品, 在较大的浓度范围内绘制了Pb元素261.37 nm处的原子峰强度随质量浓度变化的曲线。 实验结果显示, UN-LIBS方法对Pb元素检测限不高于2.07 ppt, 优于同类方法所报道的检测限。 同时, 与金属活性相对较低的钙(Ca)元素SIBS检测结果进行了比较, 分析了UN-SIBS方法的相关机理。

In order to develop a high sensitive and low cost metal elements analysis method for aqueous sample, an ultrasonic nebulizer assisted spark induced breakdown spectroscopy (UN-SIBS) system is established, where an ultrasonic nebulizer is employed to transform the bulk liquid sample into aerosol composed by intensive droplets. And a high tension coil and a couple of electrodes are combined to induce the plasma. The spectra emitted are collected to analysis the metal elements in the aqueous samples. Based on the experimental system, the features of emission spectra are studied. The electron density and electron temperature are calculated to understand the physics characteristic of the plasma in UN-SIBS experiments. Samples of different concentration of lead are analyzed by UN-SIBS method to make clear of the relationship between concentration and the peak intensity of the heavy metal element Pb. Besides, the atomic line of lead at 261.37 nm detected by the sample with the concentration of 2.07 ppt could be easily distinguished which is better than the LOD reported in references. The aqueous samples with calcium, as a lower activity metal element, are also studied. At last, the possible mechanism is discussed according to the experimental results.