Spatially Resolved Characteristics of Solution Cathode Glow Discharge Source Coupled with an Interference Filter Wheel as Spectral Discrimination Device

Fabrication and Characterizations of Axial View Liquid Electrode Plasma Atomic Emission Spectrometry for the Sensitive Determination of Trace Zinc, Cadmium, and Lead

Axial view liquid electrode plasma-atomic emission spectrometry (axial view LEP-AES) was proposed and fabricated successfully in this work. The emission spectra from Zn, Cd, Pb, Ca, and K were applied for characterization and optimization. Comparing with conventional radial view LEP-AES devices, the newly designed axial view-LEP provided better sensing ability toward trace heavy metals. Moreover, pulsed voltage discharge was found to be advantageous over continuous discharge under the same discharge time for detection. The optimized parameters facilitate the limit of detection to achieve 0.24, 0.051, and 0.85 μg L^-1 for Zn, Cd, and Pb, respectively. Furthermore, the axial view LEP-AES possessed excellent reproducibility and good durability. The real sample tests using two different certified reference water samples revealed the great potential of the axial view LEP-AES as a novel practical elemental analysis tool.

Application of atmospheric pressure glow discharge generated in contact with liquids for determination of chloride and bromide in water and juice samples by optical emission spectrometry

Novel atmospheric pressure glow discharge (APGD) microplasma systems, sustained between a miniaturized flowing anode (FLA) or cathode (FLC) and a He jet, were investigated for the direct determination of Br and Cl, using optical emission spectrometry (OES). The impact of the most crucial operating parameters, i.e., the acid type and its concentration, the discharge current, the gas flow rate, and the sample flow rate, was studied for each of the proposed APGD-based systems. Under the optimized conditions, the analytical figures of merit were determined. The susceptibility to the matrix effects of both developed methods was verified as well. It was found that the mechanism of the analytes transport into the discharge likely relied on the cathode sputtering in the case of FLC-APGD and the formation of the volatile Br and Cl species for FLA-APGD. The DLs of Br and Cl were established to be relatively high, i.e., 0.15 and 1.5 mg L^-1 for FLA-APGD and 2.1 and 18 mg L^-1 for FLC-APGD. However, both studied methods turned out to be resistant to the presence of foreign ions in a sample, at relatively high concentrations. Hence, the proposed methods could be successfully applied for the determination of Br and Cl in water and juices samples and no major differences between the results obtained using the external standard calibration and the standard addition method were found.

Five years of innovations in development of glow discharges generated in contact with liquids for spectrochemical elemental analysis by optical emission spectrometry

The newest achievements in the field of glow microdischarges generated in contact with a flowing liquid cathode (FLC) and a flowing liquid anode (FLA), used as the excitation sources for optical emission spectrometry (OES), were summarized herein. The design of recently reported discharge systems was compared and comprehensively discussed. A lot of effort was devoted to evaluate the effect of selected operating parameters, i.e., discharge voltage and current, sample flow rate, sample pH, jet-supporting gas flow rate, and discharge gap, on the microplasma stability and the intensity of measurable analytical signals. Furthermore, the influence of chemical modifiers, i.e., organic acids, alcohols, and surfactants, aimed at improving the sensitivity and reducing matrix effects, was referred to as well. Finally, the analytical performance and the application of these promising excitation sources for the elemental analysis of different-matrix samples were presented.