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Prior to the development of the collision cell, ICPMS had severe limitations for environmental analysis of wastewaters and solid samples due to molecular interferences, especially for elements with atomic weights in the range of approximately 40-115.  Correction equations were able to correct for some major interferences however, applying these factors often negatively impacted the reporting levels.

The collision cell effectively resolved many polyatomic interferences, providing a simple, universal way of dramatically reducing molecular interferences by utilizing kinetic energy discrimination and collision dissociation.  Using He as a cell gas did not require much if any prior knowledge of the sample matrix, and since it is inert, He does not create any new interferences as is often the case when using a reactive gas.

However, these cell conditions need to be properly optimized to assure the best removal of the associated interference as there may be limitations when the amount of an interferent is very high and/or the required detection levels are very low.  This paper will examine what the limits are, the optimization of cell conditions, and techniques to correct for potential false positives for those analytes that suffer from doubly charged ion effects.