Citation:

FRICKE, M., P. A. CREED, C. A. SCHWEGEL, JOHN T. CREED, S. K. YATHAVAKILLA, AND S. CONKLIN. CHARACTERIZATION OF SULFUR CONTAINING ANALOGS OF MONOMETHYLARSONIC ACID IN AQUEOUS PHASE STANDARDS AND CARROT EXTRACTS BY IC-ICP-MS AND IC-ESI-MS/MS. Presented at American Chemical Society Ar Symposium, Atlanta, GA, March 26 - 31, 2006.

Impact/Purpose:

To develop an arsenic speciation protocol for the analysis of dietary components and composite diets in order to provide a more accurate assessment of human exposure to arsenicals.

Description:

Recently, sulfur analogs of well known arsenicals have been identified, generating a need for stable species-specific standards. This presentation will focus on the identification and characterization of a novel species, monomethylthioarsonic acid (MMTA), in carrots. A standard of MMTA was synthesized by reacting monomethylarsonic acid (MMA) with H₂S. High-resolution ESI-MS/MS indicates that MMTA is produced. While MMTA appears to be stable in solution, attempts at crystallization have resulted in degradation of MMTA to MMA. USing IC-ICP-MS, MMTA was identified in carrot samples as indicated by chromatographic co-elution with the synthesized standard. However, confirmation by IC-ESI-MS/MS has been hampered by sensitivity issues. The origin of MMTA in carrots will be discussed considering the likely sulfur-oxygen exchange with MMA in sulfidic, reducing environments and/or previous use of methylarsine sulfide (CH₃AsS)_x as a fungicide.

Record Details: