Energy-related net signal optimization based on response surface in axially-viewed inductively coupled plasma atomic emission spectrometry with multichannel detection

Abstract

An axially-viewed ICP was used with a multichannel detector to plot the net analyte line intensity as a function of the power and of the carrier gas flow rate. Although the 2-D response surfaces exhibited complex patterns, as previously published, it was possible to relate the maximum net signal to the aerosol carrier gas flow rate, which, in turn, could be related to the excitation energy, Eexc, for atomic lines, and the energy sum, Esum (i.e., sum of ionization and excitation energies) for ionic lines. This relationship was possible because the maximum net signal was always obtained for the maximum power used in this work, i.e., 1.5 kW. Using a Varian Vista ICP system with a Glass Expansion concentric nebulizer, the optimum gas flow rate was equal to 1.41 E−0.26exc and 3.33 E−0.57sum for the atomic and ionic lines, respectively. These equations allowed us to indicate the optimal nebulization gas flow rate value for a large set of elements and lines, with the exception of some Ce ionic lines with an energy sum near 14 eV. For analytical purposes, a limited number of elements and lines were suggested for the establishment or the verification of the equations.