Simultaneous Determination of 29 Trace Elements in Tourmaline by Inductively Coupled Plasma-Mass Spectrometry with Sealed Press Acid Decomposition

Tourmaline is a boron-containing aluminosilicate mineral, which is an important non-metallic mineral resource, and an indicator for rock-forming and ore-forming processes. The chemical composition of tourmaline is highly variable due to the isomorphic substitution. The major elements of tourmaline are Si, Al, B, Fe and Mg, whereas the trace elements are rare earth (REE), Cu, Pb, Zn, Sn, Ag and Sr. The stable chemical properties make it difficult to complete digestion by acid or alkaline reagents. Samples were digested by HNO₃-HF in a sealed and pressurized device. 50% aqua regia was used to repeat dissolution. Twenty nine trace elements in tourmaline including precious light metals, heavy metals, radioactive metals and rare earth elements were determined by Inductively Coupled Plasma-Mass Spectrometry. The detection limits (n=12) ranged from 0.003 to 0.4 μg/g and the relative standard deviations (RSD, n=12) ranged from 0.9% to 9.17%. The proposed method was applied to the determination of certified reference materials and the results were consistent with the certified values. The recoveries of elements ranged from 90% to 110%. This method solves the problem for difficult dissolution of the tourmaline sample and the fine residue of aluminum hydroxide in the redissolution process. The coexisted ions B, Al and Fe in sample solutions show only slight interference, and the measurement results are accurate and reliable.