Ferrotungsten main components have negative influence on trace component content determination results by ICP-AES method. Optimization of As and Sb coprecipitation on iron (III) hydroxide conditions (pH, iron (III) amount, time of the precipitate coagulation) for separating them from ferrotungsten matrix was carried out. The conditions were successfully applied to the ICP-AES determination of arsenic and antimony in ferrotungsten certified reference materials.