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 st udy on the occurrence of spectral interferences was carried out. All p olyatomic ions originating from the matrix elements Ca, Cl, P, K, C, N a and S that give rise to spectral overlap with the analyte elements w ere examined systematically. For these matrix elements, which are repr esentative of most biological materials, a list of all the polyatomic ions, which can be seen to interfere up to a matrix element concentrat ion of 1 g l-1, is given. In addition, for each spectral interference, the corresponding apparent analyte concentration was calculated for d ifferent matrix concentrations. In this way, an interference factor (I F) could be calculated for each spectral overlap so that the extent an d importance of each potential spectral interference can be estimated. This factor is defined as follows: IF = 10(6) x apparent concentratio n (analyte element)/concentration (matrix element). A study on the for mation and short- and long-term stability of polyatomic ions was also carried out to evaluate the use of some simple correction procedures t o overcome spectral overlaps. Finally, a review of the correction proc edures applied to biological materials is given together with some exa mples.