Fundamental studies were conducted in order to gain useful insights about energy transfer that takes place when a low flow (20 mL min -1 ) of N 2 is introduced into the central channel of the Ar-ICP source in inductively coupled plasma optical emission spectrometry (ICP OES). Axial and radial emission profiles of Mg(I), Mg(II) and Ar(I) were collected along and across the central channel of both Ar-ICP and Ar-N 2 -ICP. Axial profiles indicated a more energetic plasma close and above the load coil when N 2 was added. On the other hand, radial profiles suggested a wider and more uniform central channel with the N 2 flow addition. By computing the plasma robustness (Mg(II)/Mg(I) ratio) across the central ICP channel, it was found a low (and uniform) energy coupling among the bulk plasma and the central channel of the Ar-ICP, which was significantly improved by adding N 2 . The results obtained also suggested that N 2 plays an important role locally, but does not in the outer regions of the ICP, which in turn denoted an unlikely N 2 diffusion. The better excitation conditions caused by N 2 were confirmed by measuring the excitation temperature in the central channel of the ICP, using a set of Fe ionic lines, where the excitation temperature increased from 7480K to 7910K. The effectiveness of the improved plasma robustness was evaluated for diluted seawater and the results demonstrated that the analyte signal suppression induced by the concomitants was reduced. Accuracy was accessed by analyzing certified reference samples (water and sediment), whereas good agreement among the concentrations found and those certified were observed. These results indicated low background and absence of spectral interferences caused by N 2 . The estimated detection limits for both Ar-ICP and Ar-N 2 -ICP were fairly comparable, revealing that the mixed-gas plasma is a robust source for trace elements determination using axially viewed-ICP OES. It was concluded that adding a low flow of N 2 is a simple way to increase plasma robustness without sacrificing analyte sensitivity.