Determination of Trace Elements in Magnetite by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry Using Multiple External Standards without an Internal Standard Calibration

Abstract

Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) is commonly used to analyze trace elements in magnetite, which can be divided into internal standard (IS) and no internal standard (NIS) methods according to calibration techniques. IS method involves a relatively complex process for the determination of Fe content by Electron Microprobe. Moreover, elemental content are affected by the analytical accuracy of IS elemental iron. An analytical method for determination of trace elements in magnetite by LA-ICP-MS using multiple external standards (basaltic glasses BCR-2g, BIR-1g, BHVO-2g, GSE-1G) without an IS element has been developed. The proposed method avoids the determination of the IS element. Trace element compositions of komatitic glass (GOR-128g) and natural magmatic magnetite (BC 28) were determined by the proposed method and used to evaluate the reliability of the method. Results show that the analytical values of komatitic glass are consistent with the certified values and reported values by the existing IS method. The relative standard deviation (RSD) of most elements is smaller than 5%. Most elements of natural magmatic magnetite have RSD better than 7% between the analytical values and the certified values, and RSD better than 15% between the analytical values and the reported values by the IS method. This indicates that multiple external standards without an IS method can determine accurate calibration of trace element concentrations of iron-rich silicates and magnetite, overcoming the matrix effects. Therefore, multiple external standards without an IS method is a fast and precise method for determination of trace elements in magnetite, which has a great application potential.

Keywords

• magnetite
• trace elements
• multiple external standards without internal standard
• laser ablation-inductively coupled plasma-mass spectrometry
• matrix effects