Development of compact emission detection devices for the measurement of environmental pollutants using helium radio-frequency plasma

本研究的目的在于利用无线电波(200-300 kHz)容易产生小型化、稳定的氦等离子体，开发能够对环境污染物进行高灵敏度、高选择性检测的紧凑型原子发射检测装置。测光系统采用雪崩光电二极管模块。通过选择合适的干涉滤光片，用雪崩探测器模块探测到了硫磺的几个典型的原子发射(921-923 nm)。通过优化电极内径和电极间距、施加功率和频率、等离子体气体流量等参数，实现了对硫的Pg/s灵敏度。其次，研制了一种配备同轴双管式微等离子体炬的小型节能AED装置。利用AED装置可以在低于1W的外加功率和几毫升/分钟的等离子体气体中产生等离子体。将AED装置安装在GC系统上，通过优化工作功率、频率、等离子体气体流量等参数，利用CCD光谱仪实现了对有机磷、硫化合物的高灵敏度检测，并研制了一种同轴式微等离子体炬与电极管相对定位的AED装置。硫的检出限为8pg/s，磷的检出限为12pg/s。

The purpose of this study was that the development of compact atomic emission detection (AED) devices capable of performing high-sensitive and high-selective detections for environmental pollutants because we paid attention to the easy generation of miniaturized and stable helium plasma by applying radio-wave (200-300kHz).An AED device with high-sensitivity for some organic sulfur compounds was firstly developed. An avalanche photodiode (APD) module was used for the photometric system. Some typical atomic emissions (921-923nm)from sulfur were detected by the APD module after selecting by a suitable interference filter. The pg/sec sensitivity for sulfur was achieved as a GC detector by optimizing the inner diameter of electrodes and the distance between them, the applied power and frequency, and the flow rate of plasma gas etc.Next, a smaller and power-saving AED device equipped with a coaxial double-tube type micro plasma torch was newly developed. The plasma was capable of being generated by using the AED device with below 1W of applied power and a few mL/min of plasma gas. When the AED device was equipped on a GC system, more highly sensitive detection of organic phosphorus and sulfur compounds was performed with a CCD spectrometer after the optimization of applied power and frequency, and the flow rate of plasma gas.Furthermore, another AED device with a coaxial type micro plasma torch with face-to-face positioned electrode tubes was developed. 8pg/sec for sulfur and 12pg/sec for phosphorus as the detection limit were achieved, respectively.