A Pulsed Atomization and Excitation Source of Variable Discharge Gap Geometry in the Analysis of Solutions by Atomic Emi
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A Pulsed Atomization and Excitation Source of Variable Discharge Gap Geometry in the Analysis of Solutions by Atomic Emission Spectrometry B. K. Zueva, A. A. Zhirkova, *, V. V. Yagova, I. S. Smirnovab, and A. S. Korotkova aVernadsky
Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences Moscow, 119991 Russia b Faculty of Natural and Engineering Science, Dubna State University Dubna, Moscow oblast, 141980 Russia *e-mail: [email protected]
Received December 24, 2019; revised February 18, 2020; accepted March 17, 2020
Abstract—An atomization and excitation source for the analysis of solutions by atomic emission spectrometry is proposed on the basis of pulsed glow discharge with a solid anode and discharge gap geometry varied within the discharge. A portable atomic emission spectrometer recording total emission spectrum from a single sample drop is developed in its basis. Keywords: atomic emission analysis of solutions, microplasma, pulsed discharge, electrolyte cathode DOI: 10.1134/S1061934820090178
Electrolyte cathode glow discharge (ECGD) in the last decade is more and more widely used as an atomization and excitation source in atomic emission spectroscopy [1]. It is used for the determination of heavy metals in ore samples [2], direct determination of metal impurities in high-purity reagents [3], determination of industrially important transition metals in process and waste waters [4], studies of the mineral composition of highly radioactive liquid wastes [5], determination of heavy metals in environmental samples and biological tissues [6], and in some other tasks. Because of the proper selection of conditions of analysis, the performance characteristics attained using ECGD are comparable or even superior (for alkali metals) [1] to those for inductively coupled plasma atomic emission spectrometry. In sources of this kind, glow discharge is maintained constantly burning between the surface of a test solution and a metallic core anode [7], and the injection of analytes to the discharge zone is attained by the electrospray-like generation of small drops followed by their evaporation and the atomization of the solution from the electrode surface [8]. Such design determines small dimensions of the unit, simplicity of its design, and no need in using special sample injection equipment (sputtering chambers, capillaries, nebulizers) for transporting analytes to the hot zone [7]. In comparison with widespread atomization sources based on inductively coupled or microwave plasma, the ECGD system does not require a gas stream to maintain the discharge,
because its work is sustained in air saturated by solvent vapors. An important advantage is the minimum memory effect because of the constant renewal of the cathode surface on the effluence of the electrolyte, which is especially important in the analysis of samples with complex matrices [1, 7]. However, the memory effect cannot be completely eliminated because of the pollution of the metallic anode, which requires special measures for its clean
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