Determination of Sulfur in Fossil Fuels by Isotope Dilution Thermal Ionization Mass Spectrometry

Abstract

Total sulfur has been measured in 13 petroleum and 14 coal Standard Reference Materials (SRMs) by isotope dilution thermal ionization mass spectrometry. These materials are suitable as primary and quality control standards for determining the sulfur content of oils and coals by X-ray fluorescence and high-temperature combustion instrumentation. Samples were spiked with enriched stable 3% and combusted in sealed Carius tubes using nitric and hydrochloric acids. The oxidized sulfur was reduced to HzS, precipitated as AsBk and then dissolved in an ammoniacal solution of As2O3. A portion of this solution, equivalent to 1.5 pg of sulfur, was added to a single Re filament coated with silica gel. The amount of sulfur in the samples was determined from the j8/3% ratio by measuring the 75As3%+/75As3%+ molecular ions in a Faraday detector. A total of 158 sulfur procedural blanks covering a 10-year period show an approximate lognormal distribution with a grand mean of 0.26 pg of sulfur. This is a negligible correction for most of the data reported here. The total uncertainty (95% confidence interval) for homogeneous materials such as oils is about 0.5%, and for less homogeneous materials such as coals is 1-496.One of the most important properties of fossil fuels is their sulfur content. Combustion of fossil fuels is the primary source of anthropogenic sulfur compounds released into the atmosphere. Recent estimates suggest that the anthropogenic flux into the atmosphere may be equal to or greater than the natural flux. Electric utilities within the United States burn a large amount of fossil fuel and are responsible for approximately 70% of the SO2 emitted into the atmosphere.' After entering the atmosphere, oxides of sulfur are converted to sulfuric acid and sulfate particles. These particles play an important role in the physics and chemistry of the atmosphere. The radiation budget of the earth is influenced by the fine particles in the atmosphere. Visibility degradation resulting from sulfate aerosols has been of concern particularly in pristine areas such as national parks. Rollback in sulfur emissions from fossil-fueled power plants has been an environmental goal for the last two decades.The accurate determination of the concentration of sulfur in fossil fuels is important for several reasons. The quality and price of both petroleum and coal are related to the amount of sulfur present. There are federal, state, and local regulations This article not subject to US. Copyright. Published 1994 by the American Chemical Society that limit the amount of sulfur oxides that can be emitted during the combustion of fossil fuels. Electric power companies must monitor the emissions from their stacks in order to comply with regulations of the Environmental Protection Agency. These companies also closely monitor the sulfur content of their incoming feedstocks to ascertain the quality, acceptability, and price. The fossil fuel producers and users require fast and inexpensive methods for the determination of sulfur in the rangeof 1-5% ...

A rapid and high‐precision method for sulfur isotope δ34S determination with a multiple‐collector inductively coupled plasma mass spectrometer: matrix effect correction and applications for water samples without chemical purification

“…The sulfur isotope ratio δ 34 S measurement using MC‐TIMS is performed by determination of the polyatomic ions 75 As 32 S + and 75 As 34 S + . The main advantage of this technique is that a very small sample mass is needed (a minimum mass of 0.2 µg S) . However, sample preparation for this method is also complex and time‐consuming.…”

Determination of low‐level (sub‐microgram) sulfur concentrations by isotope dilution multi‐collector inductively couple plasma mass spectrometry using a 33S spike and internal normalization for mass bias correction

“…Since the 1990s the certification of sulfur in fossil fuels and other matrices at the National Institute of Standards and Technology (NIST, Gaithersburg, MD, USA) has been exclusively performed using isotope dilution thermal ionization mass spectrometry (ID‐TIMS). While this method gives precise and accurate values for materials with moderate to high sulfur concentrations, it is limited in its capability for very low concentration measurements (<1 µg/g) due to the blank associated with the chemical reduction procedure; typically 0.2 S µg …”

“…Since the 1990s the certification of sulfur in fossil fuels and other matrices at the National Institute of Standards and Technology (NIST, Gaithersburg, MD, USA) has been exclusively performed using isotope dilution thermal ionization mass spectrometry (ID-TIMS). While this method gives precise and accurate values for materials [1][2][3][4][5] with moderate to high sulfur concentrations, it is limited in its capability for very low concentration measurements (<1 mg/g) due to the blank associated with the chemical reduction procedure; typically 0.2 S mg. [1][2][3][4][5] In recent years, inductively coupled plasma mass spectrometry (ICP-MS) has been investigated as a means of measuring the sulfur amount of lower concentration materials. [6][7][8][9][10][11][12][13] The main advantage of ICP-MS techniques over ID-TIMS is the elimination of the chemical reduction procedure needed for the latter technique.…”

Determination of mercury in SRM crude oils and refined products by isotope dilution cold vapor ICP-MS using closed-system combustion

“…The venting process should be conducted behind an appropriate explosion-resistant safety shield by appropriately trained personnel. A discussion of Carius tube design for minimizing losses and hazards by explosion has been provided by Gordon et al [14] and references therein to their two previous papers and also in more recent work [15,16].…”