Determination of Se at low concentration in coal by collision/reaction cell technology inductively coupled plasma mass spectrometry

摘要

A method is proposed for the determination of selenium at low concentration in coal by collision/reaction cell technology inductively coupled plasma mass spectrometry (CRC-ICP-MS). Samples were decomposed by high pressure microwave-assisted wet digestion (MAWD) using 250 mg of coal, a mixture of 5 mL of 14.4 mol L-1 HN0(3) and 1 mL of 40% HF and 70 min of heating program (200 degrees C and 40 bar). Hydrogen gas used in the colli-sion/reaction cell was investigated to minimize the argon-based interferences at m/z 77,78 and 80. The rejection parameter (RPq) and the H-2 gas flow rate were set to 0.45 and 4.8 mL min(-1), respectively. The use of H-2 in the cell resulted in other polyatomic interferences, such as (GeH+)-Ge-76-H-1, (BrH+)-Br-79-H-1 and (BrH+)-Br-81-H-1, which impaired Se determi-nation using Se-77, Se-80 and Se-82 isotopes, thus Se determination was carried out by monitoring only Se-78 isotope. Selenium was determined in certified reference materials of coal (NIST 1635 and SARM 20) and an agreement better than 95% was observed between the results obtained by CRC-ICP-MS and the certified values. Under opti-mized conditions, the instrumental limit of detection was 0.01 mu g L-1 and the method limit of detection was 0.01 mu g g(-1) which was suitable for Se determination at very low concentration in coal. (C) 2018 Elsevier B.V. All rights reserved.