Identification Tests of Aristolochic Acid in Crude Drugs by Reversed-Phase TLC/Scanning Densitometry

We performed identification tests of aristolochic acid in Xixin, Mutong, Muxiang, and Fangji by reversed-phase TLC/scanning densitometry using aristolochic acid I as a marker compound. The developing solvents used were: I) acetonitrile/methanol/water mixture solution (3 : 1 : 1) and II) 2-butanone/methanol/sodium sulfate(1→20) mixture solution (2 : 1 : 1). The Rf value of aristolochic acid I was 0.54 using the I system and 0.57 using the II system. The maximum absorption wavelengths of aristolochic acid I observed by scanning densitometry were 254 and 325 nm.