Interference Effects and Their Control in ICP-MS Analysis of Serum and Saline Solutions

Abstract

Advances in analytical technology have led to the development of a variety of very sensitive techniques for determination of very low levels of trace elements in biological and/or environmental matrices. However, the improvement in equipment and data handling has not been accompanied, in general, by an equivalent attention to the quality of results. In this framework, inductively coupled plasma-mass spectrometry offers extremely high detection power for the determination of a wide range of elements. The analysis of samples with a complex matrix is nevertheless a very challenging task. The determination of trace elements in solutions containing high salt concentrations, e.g., human serum (9 g/liter NaCl) and saline solution with dissolved solid (5 g/liter NaCl) was studied. The use of reference materials and internal standardization allows the determination by ICP-MS of Br, Ca, Mg, Rb, Sr, and Zn in serum to be optimized. The signal suppression in the presence of NaCl depends on the ionization potential and mass of the element considered. Cluster analysis is applied to a matrix of data of signal suppression of 25 elements under different conditions. Four groups of elements with the same behavior were identified and for each group a suitable internal standard was chosen. The use of three internal standards instead of a single one improves significantly the experimental accuracy and precision in the analysis of saline solutions.