Determination of halogens in coal after digestion using the microwave-induced combustion technique
- Federal University of Santa Maria, Santa Maria (Brazil)
The microwave-induced combustion (MIC) technique was applied for coal digestion and further determination of bromide, chloride, fluoride, and iodide by ion chromatography (IC). Samples (up to 500 mg) were combusted at 2 MPa of oxygen. Combustion was complete in less than 50 s, and analytes were absorbed in water or (NH{sub 4}){sub 2}CO{sub 3} solution. A reflux step was applied to improve analyte absorption. Accuracy was evaluated for Br, Cl, and F using certified reference coal and spiked samples for I. For Br, Cl, and F, the agreement was between 96 and 103% using 50 mmol L{sup -1} (NH{sub 4}){sub 2}CO{sub 3} as the absorbing solution and 5 min of reflux. With the use of the same conditions, the recoveries for I were better than 97%. Br, Cl, and I were also determined in MIC digests by inductively coupled plasma mass spectrometry, inductively coupled plasma optical emission spectrometry, and F was determined by an ion-selective electrode with agreement better than 95% to the values obtained using IC. Temperature during combustion was higher than 1350 {sup o}C, and the residual carbon content was lower than 1%. With the use of the MIC technique, up to eight samples could be processed simultaneously, and a single absorbing solution was suitable for all analytes and determination techniques (limit of detection by IC was better than 3 {mu} g g{sup -1} for all halogens).
- OSTI ID:
- 21036906
- Journal Information:
- Analytical Chemistry (Washington), Vol. 80, Issue 6; ISSN 0003-2700
- Country of Publication:
- United States
- Language:
- English
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