Quantitative analysis of silicate certified reference materials by LA-ICPMS with and without an internal standard

Abstract

Quantitative analysis of silicate minerals by laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) typically has relied on the use of an internal standard estimated from mineral stoichiometry or obtained using an alternative analytical technique (e.g., electron microprobe (EMP)). Major, minor and trace element analysis of silicate certified reference materials (CRMs) can be conducted by LA-ICPMS without using an internal standard by analyzing for a comprehensive list of elements, converting the elements to equivalent oxide concentrations, scaling the oxides to 100%, and converting the scaled oxide concentrations back into element concentrations. This method demonstrates that quantitative element concentrations can be obtained from silicate CRMs having a wide range of compositions without using an internal standard and, in general, results obtained using this method are equally or more accurate than those obtained using any one of three elements (Si, Ca or Fe) as internal standards. The approach expands the application of LA-ICPMS to the analysis of unknown silicate minerals.