Abstract The liquid sampling – atmospheric pressure glow discharge (LS-APGD) has been demonstrated as a versatile source for optical emission spectroscopy (OES) and mass spectrometry (MS). The initial LS-APGD design consisted of a solution cathode and a stainless-steel counter electrode. While shown to perform well across various MS applications, efforts to improve upon the initial design of this system have been ongoing. In this study, an integrated, single electrode design is presented in which the plasma is generated between the solution electrode and the sampling orifice of the mass spectrometer. The driving force, in this case, is the reduction of system components and moving parts, thus simplifying the ionization source. This preliminary study includes an optimization of the operating parameters with a focus on maintaining a stable plasma and improving analytical performance. The multi-parametric evaluation completed here included discharge current, solution flow rate, and the electrode/sampling orifice gap. Most significantly, the manner in which the plasma is powered has changed from the solution cathode being held at ground potential to being powered negatively versus the grounded sampling orifice. Comparisons between the formation of solvent related species in the original source design and this version were performed. With optimal conditions determined, initial LODs were established for Rb, Ag, Tl, and U, with values ranging from 0.02–0.17 ng mL−1 for 20 μL injections, demonstrating increased sensitivity (72-1900×) relative to the previous two-electrode design on the same MS system which employed 50 μL injections.

中文翻译：

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开发集成的单电极液体采样 - 大气压辉光放电微等离子体电离源

摘要 液体采样 - 大气压辉光放电 (LS-APGD) 已被证明是用于发射光谱 (OES) 和质谱 (MS) 的通用来源。最初的 LS-APGD 设计由溶液阴极和不锈钢对电极组成。虽然在各种 MS 应用程序中表现良好，但一直在努力改进该系统的初始设计。在这项研究中，提出了一种集成的单电极设计，其中在溶液电极和质谱仪的采样孔之间产生等离子体。在这种情况下，驱动力是减少系统组件和移动部件，从而简化电离源。这项初步研究包括优化操作参数，重点是保持稳定的等离子体和提高分析性能。此处完成的多参数评估包括放电电流、溶液流速和电极/采样孔口间隙。最重要的是，等离子体的供电方式已从溶液阴极保持在地电位变为相对于接地采样孔的负供电。对原始源设计和此版本中溶剂相关物种的形成进行了比较。确定最佳条件后，为 Rb、Ag、Tl 和 U 建立了初始 LOD，20 μL 进样的值范围为 0.02–0.17 ng mL-1，