Ibuprofen EP Impurity E; 1-[4-(2-Methylpropyl)phenyl]ethanone; 1-Acetyl-4-isobutylbenzene; 1-[4-(2-Methylpropyl)phenyl]-1-ethanone; 4'-Isobutylacetophenone; 1-[4-(2-Methylpropyl)phenyl]ethanone; 4-(2-Methylpropyl)acetophenone,1-[4-(2-Methylpropyl)phenyl]ethanone; 1-Acetyl-4-isobutylbenzene; 1-[4-(2-Methylpropyl)phenyl]-1-ethanone; 4'-Isobutylacetophenone; 1-[4-(2-Methylpropyl)phenyl]ethanone; 4-(2-Methylpropyl)acetophenone,Impurity in commercial preparation of Ibuprofen. "Reynolds; D,; et al,: Pharm, Technol,; 26; 48 (2002); Wasylaschuk; W,; et al,: J, Pharm, Sci,; 96; 106 (2007);",Ibuprofen Impurity