# Accounting for Interelement Interferences in Atomic Emission Spectroscopy: A Nonlinear Theory
###### Abstract  
The article describes a nonlinear theory of how the presence of third elements affects the results of analyzing the elemental composition of substances by means of atomic emission spectroscopy. The theory is based on the assumption that there is an arbitrary relationship between the intensity of the analytical line of the analyte and the concentration of impurities and alloying elements. The theory has been tested on a simulation problem using commercially available equipment (the SPAS-05 spark spectrometer). By comparing the proposed algorithm with the traditional one, which assumes that there is a linear relationship between the intensity of the analytical line of the analyte and the intensities of the spectral lines (or concentrations) in the substance, it was revealed that there is a severalfold decrease in the deviations of nominal impurity concentrations from the measured ones. The results of this study allow for reducing the number of analytical procedures used in analyzing materials that have different compositions and the same matrix element. For instance, it becomes possible to determine the composition of iron-based alloys (low-alloy and carbon steels; high-speed steels; high-alloy, and heat-resistant steels) using one calibration curve within the framework of a universal analytical method. calibration; charge-coupled image sensors; impurities; metrology; plasma devices; spectral analysis; spectroscopy +
Footnote †: journal: Applied Sciences  
1  
A.N. ; [PERSON], [PERSON]. the type of system for recording light emission produced by the excited atoms and (or) ions of the substance being analyzed (photomultiplier tubes; photodiodes; charge-coupled devices). However, whatever the type of the spectrometer, it is often found that when determining the elemental composition of a material, the analytical signal depends on the concentration of other elements in it [6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24]. Four causes of this can be distinguished [25; 26]: (1) changes in the concentration of the principal component at different concentrations, the impurities being determined when working with relative intensities (see above); (2) superposition of the spectral line of the analyte and that of another element on the focal surface of the spectrometer; (3) changes in the physicochemical properties (atomic structure, crystal structure, melting point, evaporation temperature, etc.) of the substance when the concentration of the influencing element changes, causing the rate at which the atoms of the substance enter the optical excitation zone to change; (4) changes in the parameters of the optical excitation system due to the presence of atoms of influencing elements in the excitation zone (for example, changes in the temperature of plasma electrons when using arc discharge or other discharge methods). It should be noted that, as a rule, the first and second causes can be eliminated by carefully choosing the analytical line of the analyte and accurately calculating the concentration of base atoms by measuring the relative intensities of the impurities and alloying elements, respectively. The third and fourth causes directly affect how atoms enter the active zone and become optically excited. In what follows, it is these causes of the dependence of the analytical signal on the content of elements in the substance that we deal with when discussing the problem of effects caused by third elements. Examples of such effects in non-ferrous alloys are the influence that Zn and Si concentrations have on the results of analyzing copper-based alloys by means of spark spectrometers [15; 16; 17; 18; 19; 20; 21; 22; 23; 24] and the effect of Cu content on the determination of the quantities of Zn, Fe, Mg, and Mn [26; 30; 31] in aluminum alloys. Similarly, when analyzing ferrous alloys, a number of elements significantly affect the results of emission analysis due to the third and fourth causes [32; 33; 34; 35; 36; 37; 38; 39; 40].