Arsenic animal-feed additives have been extensively used in the United States for their growth- promoting and disease-controlling properties. In particular, most broiler chickens are fed roxarsone (3-nitro- 4-hydroxyphenylarsonic acid) to control coccidiosis. Disposal of the resulting arsenic-bearing wastes is currently unregulated, and they are frequently used to fertilize crop lands. Because of the high use of roxarsone in certain geographic regions, it is important that environmental fate of this compound and its transformation products be studied in order to understand their possible impacts on human health and the environment. Therefore, determination of these compounds and naturally occurring environmental inorganic and organic arsenic compounds in various media associated with the disposal of roxarsone-amended wastes is the objective of a research project at the Environmental Sciences Division. This presentation focuses on the capillary electophoresis (CE) separation of roxarsone and its transformation products in chicken excreta. Both ultraviolet (U\I) and inductively coupled plasma mass spectrometry (ICPMS) are used for detection. UV detection is not selective enough for environmental samples, but it makes method optimization prior to coupling CE to ICPMS very rugged and time-efficient. Concurrent to the development of the CE method, we are investigating reverse-phase ion-pair high- performance liquid chromatography (HPLC) with either UV or ICPMS detection to determine roxarsone and six other arsenic compounds. HPLC separation of all the arsenic compounds requires about 30 minutes. Pavkov and Goessier (2000) used anion exchange chromatography