Abstract: The present invention relates to specific water and solvent-free nitrile rubbers having specific functional groups and/or end groups, a process for the production thereof and the use thereof. This process involves removing volatile compounds from a fluid (F) containing (1) at least one nitrile rubber and (2) at least one volatile compound, wherein the process comprises at least the steps of a.) treating the fluid (F) in at least one conversation unit, b.) retreating the concentrated fluid from step a.) in at least one retreating unit and c.) feeding the retreated concentrated fluid from step b.) into at least one retreating unit.