Studies about the origin of the non-spectroscopic interferences caused by sodium and calcium in inductively coupled plasma atomic emission spectrometry. Influence of the spray chamber design

In the present work a systematic study about the characterization of the performance of three spray chambers in terms of inductively coupled plasma atomic emission spectrometry (ICP-AES) analytical figures of merit and matrix effects caused by sodium and calcium at high concentrations was carried out. In addition, experiments were conducted in order to understand the origin of the non-spectroscopic interferences caused by sodium and calcium in ICP-AES. The chambers used were a double pass (DP) a cyclonic (CC) and a home made single pass (SP). In all the cases a high efficiency nebulizer was operated at liquid flow rates ranging from 20 to 200 μl min−1. The results revealed that the ICP-AES sensitivities were higher for the SP than for the two remaining spray chambers. The data concerning the matrix effects caused by concomitants (i.e. sodium and calcium) indicated that the extent of these effects was higher for the DP than for the SP and CC. In the presence of these elements in excess, finer tertiary aerosols were generated than for water. Nonetheless, similar primary aerosols were generated irrespective of the matrix tested. Several experiments were conducted in order to elucidate the mechanism leading to the matrix effects caused by sodium and calcium in terms of aerosol transport towards the plasma. It was concluded that a combination of droplet charge effects and a reduction in the extent of solvent evaporation could be responsible for these effects.