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Development of Analytical methods for studying the Environmental Fate of the Veterinary Drug Roxarsone: Part II - Determination of volatile arsenic in chicken litter contaminated with Roxarsone

Project Purpose:
Arsine (AsH3) and methylated derivatives such as mono-, di- and tri-methylarsine are known to be highly toxic to mammals. This Research is being conducted to determine whether or not volatile species of arsenic are produced in chicken litter contaminated with Roxarsone.

Project Description(s):
The veterinary drug Roxarsone, 3-nitro-4-hydroxyphenylarsonic acid, is added to the feed of most broiler chickens raised in the U.S. to control disease and increase weight gain. Disposal of arsenic-bearing wastes from poultry houses is currently unregulated and poses a potential environmental concern. Determination of roxarsone and its biological/environmental transformation products is necessary to understand their possible impacts on human health and the environment.

The first phase of this project dealt with the development of analytical methods for determining roxarsone and suspected transformation products (arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, 3-amino-4-hydroxyphenylarsonic acid and 4-hydroxyphenylarsonic acid) in aqueous extracts. The resulting analytical methods exploited the separatory power of high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) combined with the high sensitivity of inductively coupled plasma mass spectrometry (ICPMS) for arsenic. Both CE-ICPMS and HPLC-ICPMS were successfully applied to extracts of chicken manure and litter samples obtained from feeding trial experiments using Roxarsone-treated feed.

In the second phase of the project we will investigate the possible formation of volatile arsenic compounds in chicken litter contaminated with Roxarsone. Preliminary experiments using wet litter samples revealed the presence of a volatile arsenic compound in headspace gases of the sample collection flasks. This compound was tentatively identified as methylated arsine. An analytical method based on the on-line extraction and concentration of volatile organic compounds by vacuum distillation (VD) followed with separation by gas chromatography (GC) and characterization by mass spectrometry (MS) (see EPA method 8261) is being developed and will be optimized for the determination of volatile arsenic compounds. This method will be used to further investigate the formation of volatile arsenic in chicken litter contaminated with roxarsone.

Goerges-Marie Momplaisir at momplaisir.goerges-marie@epa.gov

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