Investigation of matrix-induced interferences in mixed-gas helium-argon inductively coupled plasma mass spectrometry.

The effects of various matrix constituents, Cd, Co, Pb, and synthetic ocean water, on analyte ion signal were investigated in He-Ar plasma source mass spectrometry. Analyte ion signal suppressions and enhancements were observed in the presence of varying concomitants. The method used for optimizing analyte ion lens signal determined whether suppression or enhancement was encountered. Tuning on a nitric acid standard solution results in a suppressed signal, whereas tuning on the analyte in the presence of the matrix results in signal enhancement, relative to that obtained with no concomitant present. The heavier mass lead concomitant had the greatest effect on the ion signal. Additionally, lighter analyte elements were affected to a greater extent than heavier analytes in the presence of high concomitant concentrations.