methyl orange [ C.I. 13025,C.I. Acid Orange 52,C.I. Acid Orange-52,C.I.-13025,Gold Orange,Tropaeolin D,helianthine,methyl orange, 35S-labeled,methyl orange, sodium salt,p(((p-dimethylamino)phenyl)azo)benzenesulfonic acid sodium salt ] indictor of pH with strong acids & bases; also used as reagent to form ion pairs with, and thereby isolate, certain compounds from biological material; minor descriptor (75-86); on-line & INDEX MEDICU