SPECTRAL INTERFERENCES ENCOUNTERED IN THE ANALYSIS OF BIOLOGICAL-MATERIALS BY INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

In order to evaluate the potential of inductively coupled plasma mass spectrometry for the analysis of biological materials, a systematic study on the occurrence of spectral interferences was carried out. All polyatomic ions originating from the matrix elements Ca, Cl, P, K, C, Na and S that give rise to spectral overlap with the analyte elements were examined systematically. For these matrix elements, which are representative of most biological materials, a list of all the polyatomic ions, which can be seen to interfere up to a matrix element concentration of 1 g l-1, is given. In addition, for each spectral interference, the corresponding apparent analyte concentration was calculated for different matrix concentrations. In this way, an interference factor (IF) could be calculated for each spectral overlap so that the extent and importance of each potential spectral interference can be estimated. This factor is defined as follows: IF = 10(6) x apparent concentration (analyte element)/concentration (matrix element). A study on the formation and short- and long-term stability of polyatomic ions was also carried out to evaluate the use of some simple correction procedures to overcome spectral overlaps. Finally, a review of the correction procedures applied to biological materials is given together with some examples.