(2-(4-Formyl-phenyl)-Propionic Acid)|(2RS)-2-(4-formylphenyl)propanoic acid|2-(4-formylphenyl)propanoic acid|2-(p-Formylphenyl)propionic Acid;|4-Formyl-α-methylbenzeneacetic Acid;|Ibuprofen BP Impurity K ; (2RS)-2-(4-Formylphenyl)propanoic acid ;