title: Application of Microwave-Induced Combustion and Isotope Dilution Strategies for Quantification of Sulfur in Coals via Sector-Field Inductively Coupled Plasma Mass Spectrometry.
abstract: In recent years, microwave-induced combustion (MIC) has proved to be a robust sample preparation technique for difficult-to-digest samples containing high carbon content, especially for determination of halogens and sulfur. National Institute of Standards and Technology (NIST) has applied the MIC methodology in combination with isotope dilution analysis for sulfur determinations, representing the first-reported combination of this robust sample preparation methodology and high-accuracy quantification approach. Medium-resolution mode sector-field inductively coupled plasma mass spectrometry was invoked to avoid spectral interferences on the sulfur isotopes. The sample preparation and instrumental analysis scheme was used for the value assignment of total sulfur in Standard Reference Material (SRM) 2682c Subbituminous Coal (nominal mass fraction 0.5% sulfur). A description of the analytical procedures required is provided, along with metrological results, including an estimation of the overall method uncertainty (<1.5% relative expanded uncertainty) calculated using the IDMS measurement function and a Kragten spreadsheet approach.
authors.affiliation: NIST Material Measurement Laboratory , Chemical Sciences Division, Environmental Chemical Sciences Group, NIST Charleston Laboratory, 331 Fort Johnson Road, Charleston, South Carolina 29412, United States.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Christopher
authors.affiliation: NIST Material Measurement Laboratory , Chemical Sciences Division, Inorganic Measurement Science Group, MS 8391 Gaithersburg, Maryland 20899, United States.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Vetter