Measurement of sample and plasma properties in solution-cathode glow discharge and effects of organic additives on these properties

Abstract

Solution-cathode glow discharge was studied in an attempt to further elucidate the processes involved in the plasma. Spectroscopic and electrical properties were measured with and without the influence of three organic modifiers: formic acid, acetic acid, and ethanol. Degradation products (CO, C 2 , and CH) of the modifiers were detected in the plasma spectroscopically. Properties of solutions before and after exposure to the discharge were compared. The effects of organic additives on these solution properties were measured. A single, simple mechanism was not consistent with the data, so a multi-part mechanism is proposed for solution and analyte transport into the plasma. Evaporation from the cathode surface, droplet generation, and chemical generation of volatile species may each play a role.

Sensitive Determination of Cd in Small-Volume Samples by Miniaturized Liquid Drop Anode Atmospheric Pressure Glow Discharge Optical Emission Spectrometry

“…In the case of APGDs generated in contact with the FLC, it was established that the presence of the LMW organic compounds , or surfactants , in the solutions introduced to these systems is responsible for significant enhancement of the response of different metals, other than Cd. ,, The LMW organic acids were also desired in the photochemical vapor generation (photo-CVG) processes of Cd . Generally, addition of the LMW organic compounds was recognized to likely promote formation of the H radicals in the liquid phase and/or in the liquid-discharge interfacial zone and change the physical properties of the FLC solutions. ,, Here, for the first time, the effect of addition of the LMW organic compounds, i.e., HCHO, HCOOH, and CH 3 OH, each at a concentration of 2% (v/v) to the analyzed solutions was examined in the case of the LDA-APGD system. Admixture of the nonionic surfactant (Triton X-405 at 0.5% m/v) to the solution was also tested; however, the discharge was very unstable in this case, probably due to a sudden change in surface tension and viscosity of the drop.…”

“…Effect of Addition of Low-Molecular Weight Compounds. In the case of APGDs generated in contact with the FLC, it was established that the presence of the LMW organic compounds 5,11 or surfactants 5,12 in the solutions introduced to these systems is responsible for significant enhancement of the response of different metals, other than Cd. 5,11,12 The LMW organic acids were also desired in the photochemical vapor generation (photo-CVG) processes of Cd.…”

“…5,11,12 The LMW organic acids were also desired in the photochemical vapor generation (photo-CVG) processes of Cd. 11 Generally, addition of the LMW organic compounds was recognized to likely promote formation of the H radicals in the liquid phase and/or in the liquid-discharge interfacial zone and change the physical properties of the FLC solutions. 5,11,12 Here, for the first time, the effect of addition of the LMW organic compounds, i.e., HCHO, HCOOH, and CH 3 OH, each at a concentration of 2% (v/v) to the analyzed solutions was examined in the case of the LDA-APGD system.…”

The 2017 Plasma Roadmap: Low temperature plasma science and technology

“…Often, such systems operate with dc power, offering even greater simplicity. Two examples are the so-called solution-cathode glow discharge (SCGD; see figure 29, left) [146] and the liquid-sampling atmospheric-pressure glow discharge (LS-APGD) [147].…”

Temporal characterization of fundamental plasma parameters in pulsed liquid electrode plasma (LEP) optical emission spectrometry

“…The 366 active LEP power is comparable to other solution-based microplasmas, for example, the SCGD 367 and the LS-APGD. Typical operating powers for the SCGD and LS-APGD are in the range of 368 60-80 W [35][36][37] and < 50 W [27,38], respectively. 369…”