Courtney Tanabe,* Susan Ebeler, Patrick Gray, and Jenny Nelson 
*Department of Viticulture and Enology, University of California, Davis, 595 Hilgard Lane, Davis, CA 95616 (cktanabe@ucdavis.edu)

Arsenic (As) occurs naturally in the environment and is consequently found in food and beverages such as wine. Arsenic exists in multiple forms, but not all species have the same toxicity. Due to the potential health threat of some species, it is important to measure individual species and not just the total As concentration. Regulations have been proposed for the more toxic, inorganic As species 
(AsV and AsIII) in other food products. Traditionally, the inorganic As values were achieved by measuring individual species using ion exchange high pressure liquid chromatography coupled to a triple quadrupole inductively coupled plasma – mass spectrometer (HPLC-ICP-QQQ) and then the two inorganic forms were added together. Our method also used HPLC-ICP-QQQ, but instead of analyzing the inorganic As species separately, AsIII was intentionally oxidized to AsV with hydrogen peroxide prior to analysis. This allowed all inorganic As to be expressed as AsV. By converting the inorganic species, this method separated monomethylarsonic acid and dimethylarsinic acid from AsV in 2 min, 10 times faster than the current Food and Drug Administration methods for speciation of As. Furthermore, by reacting samples with O2 in the ICP-QQQ, there was decreased spectral interferences and increased sensitivity. Validation results from two participating laboratories are presented to demonstrate the new method’s accuracy and reproducibility in wine matrices. 

Funding Support: Funding from PI.