Studying the effect of the argon flow introduced into the arc discharge in the atomic-emission spectrometry of powdered samples using the spillage-injection method

Abstract

Atomic emission spectral analysis of a powder sample by the method of spillage-injection into the plasma of an arc discharge burning in air is accompanied by the formation of cyanide, nitride and oxide compounds which form molecular bands in the spectrum thus impeding measuring the intensity of the analytical lines of the elements to be determined. Feeding an argon flow into the arc discharge can reduce the amount of spectral interference and increase the plasma temperature, which promotes more a complete evaporation of the analyzed sample injected into the arc discharge and, accordingly, increases the degree of ionization of the elements and the intensity of ion spectral lines. The aim of the study was to develop a device for argon introduction into the arc discharge zone and simultaneous sample delivery by a spillage-injection method, as well as to study the effect of argon consumption on arc discharge parameters and emission spectra of powder samples. The argon input device (up to 2.25 L/min) is developed on the basis on glass funnels, the geometric dimensions of which are selected with the goal of gaining the maximum intensity of spectral lines and reduced intensity of molecular bands at the minimal argon consumption. The study carried out on a «Grand Potok» spectrometer demonstrated that with an increase in argon consumption, the intensity of SiO molecular bands decreases, the plasma temperature increases by 350 – 540 K, and the intensity of ion and atomic lines with the ionization energy above 8 eV increases by more than 4.7 and 2.9 times, respectively. The developed device can be used in analysis of geological materials to improve the metrological characteristics of the results of atomic emission spectral analysis.