This method procedure describes a procedure for the determination of inorganic arsenic in animal feeding stuffs by anion-exchange HPLC-ICP-MS following water bath extraction. This method was successfully tested in the range of 0,149 mg/kg to 9,69 mg/kg in the following animal feed matrices: rice meal, seaweed meal, fish meal, grass meal, complete feed (marine-based), complete feed (cereal based) and a synthetic solution. NOTE Mineral feed matrices are not included in the scope of this method as the determination of the total arsenic content is more suitable in such matrices.