Determination of Se and Te in coal at ultra-trace levels by ICP-MS after microwave-induced combustion. Issue 5 (20th March 2019)

• Record Type: Journal Article
• Authors: Rondan, Filipe S.; Henn, Alessandra S.; Mello, Paola A.; Perez, Magali; Bullock, Liam A.; Parnell, John; Feldmann, Joerg; Flores, Erico M. M.; Mesko, Marcia F.
• Is Part Of: Journal of analytical atomic spectrometry. Volume 34:Issue 5(2019)
• Page Start: 998
• Page End: 1004
• Publication Date: 2019-03-20
• Subjects: Atomic spectra -- Periodicals; Atomic absorption spectroscopy -- Periodicals; 543.0858
• DOI: 10.1039/c9ja00048h
• Languages: English
• ISSNs: 0267-9477

Abstract

Abstract : The development of a method for the ultra-trace determination of selenium and tellurium in coal by ICP-MS using microwave-induced combustion for sample preparation. 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 HNO3 + 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 HNO3 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.