Matrix effects due to calcium in inductively coupled plasma atomic-emission spectrometry: their nature, source and remedy
Abstract
Matrix effects due to calcium in inductively coupled plasma atomic-emission spectrometry have been characterised for a representative selection of analyte lines. Operating conditions were typical of those widely used for routine analysis. Calcium is among the most potent elements causing matrix effects and is an important geological matrix element. Most analyte sensitivities were suppressed, by as much as 30% in some instances, but lithium could be supressed or enhanced depending on small changes in the conditions. The effects are strongly related to analyte excitation potentials, and were found to be caused by changes in excitation conditions in the plasma. Several effective methods of obviating the matrix problem are demonstrated and compared.