Procedures have been developed for the preparation, at levels of label which exceed 90%, of ring-deuterated diphenylamines (DPAs) with the label at specific ring positions. The compounds so prepared are DPA-d 10, DPA-2, 4, 6, 2', 4', 6'-d 6, DPA-2, 6, 2', 6'-d 4, and DPA-4, 4'-d 2.
