Mass discrimination in dynamic reaction cell (DRC)-ICP-mass spectrometry

Abstract

The possibility of overcoming spectral interferences by means of selective ion-molecule chemistry in a dynamic reaction cell (DRC) leads to an extension of the application range of ICP-MS for isotopic analysis. In this work, the effect of various instrumental parameters and the matrix composition on the mass discrimination (defined as the deviation between the experimental result and the corresponding 'true' isotopic ratio) was systematically studied. It is demonstrated that various DRC parameters-collision gas flow rate, reaction gas flow rate and bandpass settings-affect the mass discrimination. This observation is probably to be attributed to in-cell fractionation effects, occurring as a result of collisional losses, space-charge effects and kinetic effects in the ion-molecule chemistry. As the isotopic standard and the sample are always measured under identical conditions, external correction for mass discrimination assures accurate results. Under all conditions tested, internal correction for mass discrimination on the other hand-a strategy often used in Sr isotopic analysis did not provide accurate results. Also the matrix composition is demonstrated to have a significant influence on the mass discrimination, especially when using condensation product ions for isotope ratio measurement. This disadvantage can be overcome by using a matrix-matched isotopic standard for external correction or by isolation of the target element from the concomitant matrix, or at least its separation from the dominant matrix components

Preliminary evaluation of 135Cs/137Cs as a forensic tool for identifying source of radioactive contamination

“…Severe mass discrimination has been reported in collision/reaction cells (Vanhaecke et al, 2003(Vanhaecke et al, , 2002Boulyga and Becker, 2001), but as no certified values of 135 Cs/ 137 Cs exist, no mass bias corrections were made in this work. Comparison of a standard determined with and without introduction of CH 3 Cl into the reaction cell showed no significant difference in mass bias (Taylor et al, submitted for publication).…”

Systematic evaluation of a strontium-specific extraction chromatographic resin for obtaining a purified Sr fraction with quantitative recovery from complex and Ca-rich matrices

“…A number of studies conducted with both quadrupole-based and multi-collector ICP-MS have shown that the instrumental mass discrimination can vary considerably with the sample matrix and that the response of two elements of similar mass to a different matrix may not be sufficiently correlated. [2][3][4][5][6] The matrix-related occurrence of spectral interferences and mass discrimination indicate that accurate and precise measurements of small differences in isotopic composition should preferably be conducted on target elements that have been chemically isolated from the sample matrix.…”

Overcoming spectral overlap in isotopic analysis via single- and multi-collector ICP?mass spectrometry

“…First of all, the situation becomes significantly more complicated when various types of (molecular) ions interfere simultaneously with the analyte signal(s) of interest. Additionally, it was recently demonstrated that the mass discrimination is substantially affected by the conditions in the cell and that when using chemical resolution in a collision or dynamic reaction cell, the matrix composition may influence the mass discrimination to a larger extent [56].…”