Effect of ion-lens tuning and flow injection on non-spectroscopic matrix interferences in inductively coupled plasma mass spectrometry

The effects of various matrix constituents, Co, Pb and synthetic ocean water, on analyte signal have been studied. Suppression of the 138Ba+ signal was observed in the presence of each matrix, with the Pb matrix having the greatest effect. These matrix-induced suppressions of analyte signal were compensated for in part by the use of In as an internal standard, and by initially tuning the ion lenses for maximum analyte signal in the presence of the matrix, rather than for a simple acidified standard solution. The severity of matrix-induced suppression was compared for flow injection and continuous sample introduction. No significant differences in suppression of analyte signal between the two methods were observed because of the relatively large sample volume used for flow injection. The experimental procedure adopted, continual reference of analyte signals with and without the matrix present, effectively eliminated any bias in the results due to nebuliser and cone blockage.