A mineral formula-based calibration method for major and trace element determination of mica without applying an internal element by LA-ICP-MS

Abstract

An internal standard as ablation yield is required to calibrate raw data by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) technology. In this study, we established a new calibration method based on the mica (muscovite and biotite) structure formula-based normalization procedure, achieving high precision determination of major and trace element concentrations of mica (muscovite and biotite) by LA-ICP-MS without using an internal standard. Since the volatile components (F, Cl and OH) cannot be effectively and directly determined by ICP-MS, and the potassium concentration determined by LA technology in mica shows systematic deviation, we theoretically calculated the concentrations of volatile components and potassium, and corrected the influence of these elements on the summed normalization procedure. Applying multiple external standards plus the above modified normalization procedure, we determined the major and trace element contents of muscovite and biotite from a pegmatite dyke by this new method. The results are identical to the major element contents obtained by EPMA (Electron Probe Microanalyzer) and to the trace element contents determined by traditional internal standard-used LA-ICP-MS within ±5%. The new analytical procedure by LA-ICP-MS is low-cost and time-saving compared to the traditional method that needs combining both EPMA and LA-ICP-MS.