Comparison of Axially and Radially Viewed Inductively Coupled Plasma Atomic Emission Spectrometry in Terms of Signal-to-Background Ratio and Matrix Effects

Abstract

A comparison was made of axial and radial viewing modes in terms of the signal-to-background ratio for several commercially available ICP-AES systems. The average improvement factor was found to be in the range of 2–3 for ionic lines when the axial viewing mode was used. To obtain higher improvement factors, other modifications of the ICP systems must be associated with axial viewing, such as better practical resolution of the dispersive system and better efficiency of the sample introduction system. Matrix effects with axial viewing, such as those resulting from the presence of Na, can be minimized to the same extent as for radial viewing provided that a high rf power and a low carrier gas flow rate are used to optimize the exchange of energy between the surrounding plasma and the central channel. An increase in the id of the torch injector is also beneficial for this purpose.