Improved solution cathode glow discharge micro-plasma source with a geometrically optimized stainless steel auxiliary cathode for optical emission spectrometry of metal elements

• Published in: Microchemical journal 2022-01, Vol.172, p.106883, Article 106883
• Main Authors: Zheng, Peichao, Luo, Yuanjiang, Wang, Jinmei, Yang, Yang, Hu, Qiang, Mao, Xuefeng, Lai, Chunhong
• Format: Article
• Language: English
• Subjects: Auxiliary cathode structure; Heavy metal; Micro-plasma; Optical emission spectrometry; Solution cathode glow discharge
• ISSN: 0026-265X; 1095-9149
• DOI: 10.1016/j.microc.2021.106883

Fig. 1. Schematic diagram of the modified SCGD-OES system: (a) Experimental setup; (b) auxiliary cathodes with different geometry. [Display omitted] •An improved SCGD micro-plasma source was developed for the quantitative determination of heavy metal elements.•Stainless steel (316L) was used as auxiliary cathode material, which greater durability and stability, and reduced DLs.•The detection limits for K, Na, Ni, Cd, Pb, Co and Hg were comparable to other solution cathode glow discharge systems.•The results from this study may provide a new direction for the design of glow discharge sources. An improved micro-plasma source for the quantitative analysis of heavy metal elements by solution cathode glow discharge-optical emission spectrometry (SCGD-OES) was developed. The glow-discharge plasma source was fabricated using a geometrically optimized stainless steel auxiliary cathode solution and a tungsten anode. Optimum discharge could be attained at reduced solution flow rates under the following operating conditions: pH 1.0 (HNO3); a discharge current of 80 mA; a solution flow rate of 1.65 mL/min; and a discharge gap of 2.5 mm. The detection limits (DLs) of the improved micro-plasma source for K, Na, Ni, Cd, Co and Hg were 0.17, 0.06, 18, 10, 25 and 66 μg/L, respectively. The recoveries of metal elements from spiked samples of spring river, Yangtze River and reservoir water measured by SCGD-OES showed good agreement with those obtained using ICP-OES. The results from this study may provide a new direction for the design of glow discharge sources for the in situ determination of metal elements in complex water samples.