RETENTION BEHAVIOR OF METAL-CHELATES IN ION-PAIR REVERSED-PHASE LIQUID-CHROMATOGRAPHY AS A FUNCTION OF MOBILE-PHASE COMPOSITION WITH METHANOL-WATER AND ACETONITRILE-WATER MOBILE PHASES

The retention behaviour of Cu(II), Co(III), Ni(II) and Fe(II) chelates with 2-(5-bromo-2-pyridylazo)-5-[N-propyl- N-(3-sulphopropyl)amino]ph enol (5-Br-PAPS) and -pyridylazo)-5-[N-propyl-N-(3-sulphopropyl)amino] - phenol (nitro-PAPS) in ion-pair reversed-phase liquid chromatography was examined with mobile phases of methanol-water and acetonitrile-wa ter binary systems containing 0.05 M sodium ion and 0.02 M Tris buffer (pH 7). The correlation of log k' with the solubility parameter was d ifferent between the methanol-water and acetonitrile-water systems. Th e resolution among chelates and reagents was complete with the acetoni trile-water system and far better than with the methanol-water system.