Helium microwave induced plasma mass spectrometry for detection of metals and nonmetals in aqueous solutions

Abstract

A helium microwave induced plasma is evaluated as an ion source for plasma mass spectrometry. Analyte position studies were performed to assess background interferences and the distribution of analyte ions within the helium plasma as a function of nebulizer flow rates. Helium microwave induced plasma mass spectrometry provides detection of the halides in aqueous samples as positive ions at the low to sub-ppb levels. Detection limits for metals are in the sub-ppb range. Determination of selenium and bromide isotope ratios are possible down to the low ppb level. Flow injection was used in a preliminary matrix study. A sodium concentration of 2000 ppm was found to suppress the analyte signals by 15 to 50%. This suppression can be partially corrected for by using internal standards.