New plasma observation approaches to solve the “axial-radial” dilemma

Petar Ivanov, ICP, Spectro Analytical Instruments GmbH, Kleve, Germany

ICP-OES with axial plasma observation are still the instruments of choice for trace analytical work. Even today, while with the ICP-MS more sensitive technique is available, ICP-OES still plays an important role as it offers a much higher matrix tolerance and is therefore beneficial for certain types of samples and/or elements.

While axial plasma observation has the advantage of improved sensitivity, this technology suffers from stronger matrix influences. Also for high amounts of totally dissolved solids and organic solutions the horizontal alignment of the plasma torch is not the optimal design, since deposits are more likely to form.

Viewing the plasma radially provides generally lower sensitivity, but matrix effects are greatly reduced. Therefore the radial observation technique is typically chosen in the case of samples with high TSD concentrations, for the routine analysis of organic solutions or where high stability and precision is required.

Seemingly, the possibility to view the plasma with two interfaces solves all disadvantages but dual view techniques are a compromise since only one light path is direct. While they serve a purpose of certain applications, as they expand the capabilities of one instrument, dual view techniques do not provide the optimum performance in both viewing modes.
In the presentation new techniques to solve this dilemma will be discussed.