Expansion of the analyte concentration range using self-absorption lines

Abstract

The width of a spectral line in atomic emission spectral analysis with arc radiation sources is, as a rule, much smaller than the hardware function of the spectral device. Thus, the spectral line shape is determined by the hardware function of the spectral device and can be approximated, for example, by the Voigt function. However, when analyzing standard samples with a wide range of element concentrations, the problem of self-absorption often occurs, due to which the analytical line has to be changed, which is not always possible. We propose to modify the Voigt function by adding a factor that describes self-absorption, by analogy with the Bouguer-Lambert law. The possibility of using the proposed function was evaluated in analysis of standard samples of rocks, ores and sandstones on a Grand-Potok spectral system with a MAÉS analyzer and BLPP-2000 linear photodetector arrays. The use of proposed approximating function is shown to provide an increase in the working range of the calibration curves of Cu 327.3954 nm, Cu 324.7532 nm, Pb 287.3311 nm, Ni 305.0818 nm, and Mo 313.2594 nm by 1 – 3 orders of magnitude.