The recommended treatment for suspected arsenic poisoning is

The trivalent form of arsenite (arsenic, AsO2) has al high affinity for sulfhydryl groups and binds with great avidivty to lipoic acid, one of the five cofactors of pyruvate dehydrogenase. The most efficient way to remove this arsenite is by administering a competitive sulfhydryl compound, such as dimercaprol. Chelating agents such as EDT A, penicillamine, or deferoxamine will react with circulating metals and remove them from the body. Yet, they are less effective in competing with sulfhydryl groups than the mercaptans. Ref: Krishnan vij Textbook of Forensic Medicine and Toxicology; 5th ed; Page no: 465