(βR,δR)-3-Carboxy-5-(4-fluorophenyl)-β,δ-dihydroxy-2-(1-methylethyl)-4-phenyl-1H-Pyrrole-1-heptanoic Acid has been employed in a novel assay that can determine degradation of pharmaceutical tablets such as amlodipine besylate (AML) and atorvastatin calcium (ATV). Molecular Formula: C27H30FNO6 Molecular Weight: 483.53