阿魏酸杂质4

Ferulic Acid Impurity 4 (CAS 135820-01-8), chemically 3,4-bis(4-hydroxy-3-methoxyphenyl)cyclobutane-1,2-dicarboxylic acid (C20H20O8, MW 388.37), is a cyclobutane-type dimer of ferulic acid formed by [2+2] cycloaddition of two ferulic acid molecules. As a ferulic acid-related substance, it is used as a reference standard for the identification and quantitation of this dimeric impurity in ferulic acid APIs and plant-derived finished products, supporting impurity profiling, method validation, and quality control in pharmaceutical and analytical studies.