Abstract
A method for ultra-trace determination of Se and Te in coal by inductively coupled plasma mass spectrometry (ICP-MS) was developed. Samples (up to 500 mg) were prepared by microwave-induced combustion (MIC) in a closed system pressurized with 20 bar of oxygen. Inorganic acids or their mixtures were evaluated as absorbing solution. Using HNO 3 + HCl (1 + 1), results obtained for Se and Te after sample preparation by MIC agreed with those obtained by reference methods, microwave-assisted wet digestion (MAWD) using concentrated HNO 3 and HF, and solid sampling electrothermal vaporization inductively coupled plasma mass spectrometry (SS-ETV-ICP-MS), and also with a certified reference material of coal (NIST 1632c) for Se. Very low limits of quantification (LOQ) were obtained: 0.002 and 0.007 mg kg -1 for Se and Te, respectively. Major elements were determined in final solutions obtained by MAWD and MIC, and their concentration in solutions of MIC was negligible (<10 μg L -1 ), minimizing the risk of interference in ICP-MS analysis. The proposed method was applied to samples of coal from the United Kingdom, with a wide range of inorganic composition (from 3 to 41% ash content), showing its robustness and feasibility for routine analysis. Se concentration ranged from 0.291 to 11.5 mg kg -1 , and Te was mainly found at ultra-trace levels (<0.007 to 0.11 mg kg -1 ). The proposed method presents several advantages over the reference methods, such as the use of a higher sample mass, low LOQs and, an important aspect, no need of using HF.
Original language | English |
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Pages (from-to) | 998-1004 |
Number of pages | 7 |
Journal | Journal of Analytical Atomic Spectrometry |
Volume | 34 |
Issue number | 5 |
Early online date | 28 Feb 2019 |
DOIs | |
Publication status | Published - 1 May 2019 |
Bibliographical note
This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001. The authors are also grateful to the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, Grant 309297/2016-8), Instituto Nacional de Ciência e Tecnologia de Bioanalítica – INCTBio (CNPq Grant No. 573672/2008-3) and Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul (FAPERGS, Grant 16/2551-0000516-8) for supporting this study. Funding for the sample collection provided by the NERC Security of Supply programme UK (grant NE/L001764/1) is acknowledged.Keywords
- SAMPLE PREPARATION
- TOXIC ELEMENTS
- DIGESTION
- FEASIBILITY
- IMPURITIES
- STRATEGIES
- TELLURIUM
- HALOGENS
- SELENIUM
- SULFUR