Direct reduction of sulfates to sulfur dioxide for isotopic analysis

Journal Article · Fri Sep 01 04:00:00 EDT 1978 · Anal. Chem.; (United States)

DOI:https://doi.org/10.1021/ac50033a056· OSTI ID:6478669

Coleman, M L; Moore, M P

Direct Reduction of Sulfates to Sulfur Dioxide for Isotopic Analysis I/sub n/ a previously published method, sulfur dioxide for isotopic analysis was prepared from barium sulfate by thermal decomposition. System has been modified by the addition of a furnace with copper turnings at 600/sup 0/C. The sulfate is mixed with cuprous oxide and silica, system is evacuated and sample is reduced quantitatively at 1120/sup 0/C. Amounts of both the Cu/sub 2/O and silica relative to the BaSO/sub 4/ were the minimum required, and any increase of either had no effects on the yield of SO/sub 2/. 1120/sup 0/C was determined to be the ideal reaction temperature. Although the mechanism of the reaction is unclear, repeated applications have produced a yield of 99.8 +- 1.3%. The isotopic composition (delta/sup 34/S/sub CD/ from six determinations on a laboratory reference sample produced +14.10 +- 0.11% in comparison with +14.08 +-0.23% for the same material converted o silver sulfide and subsequently oxidized. The error is one standard deviation in all cases. The presence of the copper furnace is not necessary while oxidizing sulfides, however, it has no adverse effect, and therefore, can be left in place. The copper can be periodically regenerated by passing hydrogen over it while it is hot. The same apparatus can be used for both sulfide and sulfate samples using the same procedure; only the temperature of the main furnace is altered.

• Research Organization: Inst. of Geological Sciences, London
• OSTI ID: 6478669
• Journal Information: Anal. Chem.; (United States), Journal Name: Anal. Chem.; (United States) Vol. 50:11; ISSN ANCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102* -- Chemical & Spectral Procedures
ACCURACY
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
BARIUM COMPOUNDS
BARIUM SULFATES
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
COPPER COMPOUNDS
COPPER OXIDES
CRACKING
DECOMPOSITION
FURNACES
ISOTOPE RATIO
MODIFICATIONS
OXIDES
OXYGEN COMPOUNDS
PYROLYSIS
QUANTITATIVE CHEMICAL ANALYSIS
SULFATES
SULFUR COMPOUNDS
SULFUR DIOXIDE
SULFUR ISOTOPES
SULFUR OXIDES
TEMPERATURE DEPENDENCE
THERMAL CRACKING
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
VERY HIGH TEMPERATURE
YIELDS