Evaluation of Classical Vaporization and Ionization Interferences in a Miniature ICP

摘要

The magnitude of several classical interelement interferences in a miniature ICP is found to be small but dependent on experimental conditions. The origin and manifestation of these interference (matrix effects are shown to be complex and influenced most strongly by: (1) observation window in the plasma's tail flame, (2) rf power, and (3) nebulizer gas flow rate. In particular, vaporization interference matrices (al and PO4) caused a deprression in the intensities of both the neutral atom and ion lines of Ca with the Ca II line experiencing a larger effect than that of Ca I. Conversely, easily ionized elements (such as Na and Cs) enhanced both Ca and Mg neutral atom and ion line intensities, with the atom lines exhibiting a larger increase than those of the ions. Because both the neutral atom and ion lines of Ca and Mg are enhanced by Na and Cs, and to identical degrees, a simple shift in ionization equilibria seems not to produce the observed interference. Clearly, more fundamental knowledge concerning the formation and excitation of atoms in ICP sources is needed before interference mechanisms can be elucidated.