Multi-elemental analysis of high-purity molybdenum by electrothermal vaporization inductively coupled plasma mass spectrometry

Abstract

High purity molybdenum and its compounds are used for the synthesis of ionizing radiation detectors for search for dark matter and double beta decay. Properties of these detectors largely depend on their trace composition. The new mass-spectrometry with inductively coupled plasma (ICP-MS) and electrothermal vaporization (ETV) method was developed for the analysis of high-purity molybdenum. The samples were introduced into the ICP using the ETV device. The vaporization curves of matrix element (molybdenum) and trace elements were studied in detail. The dependence of analytical signal and limits of detection (LODs) of analytes versus ETV-ICP-MS instrumental parameters (ICP power, transport flow, ion optics settings) was established. The proposed method of ETV-ICP-MS analysis allowed us to control the content of 28 trace elements in high-purity molybdenum with a purity of 6N (99.9999% wt.) and provided LODs from 0.3 to 200 ng g-1. Using of ETV for ICP-MS analysis of molybdenum led to decreasing of the LODs of trace elements from 3 to 200 times comparing with ICP-MS analysis with standard sample introduction system. The validation of proposed ETV-ICP-MS method was performed by spike experiment and by comparing the results of ETV-ICP-MS, ICP-MS, and atomic absorption spectrometry with electrothermal vaporization (GFAAS) analysis.