Atorvastatin Calcium Impurity C;(3R,5R)-7-[2,3-bis(4-Fluorophenyl)-4-(phenylcarbamoyl)-5-(propan-2-yl)-1H-pyrrol-1-yl]-3,5-dihydroxyheptanoicAcid;(3R,5R)-7-[2,3-Bis(4-fluorophenyl)-5-(1-methylethyl)-4-(phenylcarbamoyl)-1H-pyrrol-1-yl]-3,5-dihydroxyheptanoicAcid;(3R,5R)-7-(2,3-bis(4-fluorophenyl)-5-isopropyl-4-(phenylcarbamoyl)-1H-pyrrol-1-yl)-3,5-dihydroxyheptanoic Acid; Atorvastatin EP Impurity C ;