Determination of Alkali and Alkaline-Earth Metals in Water by Microwave Plasma Atomic Emission Spectrometry with the Addition of a Stabilizing Element

Abstract

Abstract: In nitrogen microwave plasma atomic emission spectrometry, the intensities of analytical lines with low excitation energies increase in the presence of easily ionized elements. To compensate for this effect, we proposed to add additional matrix elements with ionization potentials below 6 eV (Rb, Ba, Sm, La, Eu, In, Al, and Ga) to sample solutions and calibration solutions in the determination of alkali and alkaline-earth metals. The concentration of an additional element, 75–100 mg/L, was selected based on the constancy of the analytical signals of analytes and the magnesium ratio Mg(II)/Mg(I). This concentration is insufficient for a significant change in temperature or electron density; that is, the added element is not a spectral buffer. The procedure was applied to the analysis of pore waters of bottom sediments of Lake Bolshoy Bagan (alkaline type of mineralization); the accuracy of the analysis was confirmed by the spiking method.