Analysis of sulfur compound types in asphalt

The project evaluated analytical methods for determination of sulfur compound types in asphalt and to obtain results on asphalts from the SHRP (Strategic Highway Research Program) Reference Library. Methods were applied to whole asphalts and fractions obtained through liquid chromatographic separations. The distribution of sulfur types varied with asphalt source and within fractions from a given asphalt. Sulfur types determined were as follows: sulfoxides (infrared ); aliphatic sulfides (tetrabutylammonium periodate oxidation); aromatic sulfides (total sulfides - aliphatic sulfides); and thiophenes (by difference; or direct via oxidation with hydrogen peroxide). Sulfur types present at negligible concentrations in the asphalts tested include thiols, sulfones, and sulfonic acids.