[en] An investigation has been made of the effect of barium nitrate and potassium salts (nitrate, carbonate, sulphate and halide) additives on the intensity distribution of the lines In I 303.9 nm, Co I 304.4 nm and Cd I 326.1 nm, of the background and of the analytical signal ΔY=lgI₁/Isub(b) along the arc axis, from the anode towards the cathode. It is shown that the axial distribution depends on the chemical composition of the additives. The axial distribution of the standard deviations of the measured ΔY for indium with and without additives is given. The reproducibility of the ΔY measurements is different for the different anionic components and for the different parts of the interelectrode space. The results obtained make it possible during the analysis of dry residues from solutions to select the optimal region of emission of the arc plasma with respect to the value of the analytical signal and the reproducibility of its measurement