Ultraviolet µ-raman analysis of methane sulfonic acid

CHED 1140

M. Paul Herring and Robert E. Barletta, rbaletta@jaguar1.usouthal.edu. Department of Chemistry, University of South Alabama, 307 University Blvd N, Mobile, AL 36688
Methane sulfonic acid (MSA) and other marine sulfur compounds (dimethyl sulfide (DMS) and dimethylsulfonioproprionate (DMSP)), are found at trace concentrations in the open ocean. Their distribution in the glacial record provides insight into the climatological history of our planet. For ice cores, current analytical methods involve sectioning followed by destructive analysis. Methods, e.g., Raman spectroscopy, which determine composition and concentration nondestructively with high spatial resolution, are of great interest. To evaluate the potential of Raman for the trace detection of marine sulfur compounds, laboratory measurements have been made using 248 and 488 nm excitation. Assignments of characteristic Raman bands have been made: n(C-S) = 656 n cm-1 (DMSP); n(C-S) = 686 n cm-1 (DMS); n (C-S) = 770 n cm-1 (MSA). The detection sensitivity of MSA at 488 nm was found to be ~52.0 ppm. Finally, resonance enhancement of MSA has also been found.