Possibilities and limitations of spectral fitting to reduce polyatomic ion interferences in inductively coupled plasma quadrupole mass spectrometry in the mass range 51-88

This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta, Part B (SAB). The hardcopy text is accompanied by a diskette containing the fitting program and instructions for use. The work deals with spectral fitting in ICP-quadrupole-MS. The possibilities and limitations of spectral fitting to reduce polyatomic ion interferences in inductively coupled plasma quadrupole mass spectrometry in the mass range 51-88 were investigated. Spectral fitting (simulation of the observed spectrum by a linear combination of the spectra of all individual components, both atomic and polyatomic ions) was carried out using standard spreadsheet software. Isotopic distributions for the polyatomic ions were calculated from the abundances of the individual isotopes. It was observed that in certain mass regions the number of compounds was higher than the number of independent relationships leading to more than one solution. This problem was tackled by establishing relationships between a number of (related) components (variables), all being molecular ions, and setting constraints (limits) for some other components. Spectral fitting was applied to the spectra of a number of environmentally relevant salt solutions showing severe interferences in the mass range investigated. In all cases these interferences could be reduced to negligible or acceptable levels by the application of spectral fitting. Correction for mass discrimination turned out to be an important parameter for the goodness of fit. (C) 1997 Elsevier Science B.V. All rights reserved.