An ICP index for ICP-MS determinations – new selection rules for internal standards in ICP-MS determinations and carbon enhancement effect

Abstract

The influence of non-spectral interference by carbon matrix on trace elements in ICP-MS was studied by considering the chemical and physical interatomic reactions in plasma. The ICP-index was newly proposed as an indicator of carbon matrix effect on each element, where the mean free path, first ionization potential and the number of ionization states of an analyte in argon ICP were taken into consideration as main factors. The ICP-index shows a high correlation with the carbon matrix effect as well as other matrix effects caused by elements such as K, and Mg. The ICP-index is a useful criterion for selecting appropriate internal standard elements in quantitative analysis. Taking the ICP-index of each element and the matrix element into consideration, ICP-MS determination can be carried out more accurately.