HILIC characterization: Estimation of phase volumes and composition for a zwitterionic column

摘要: A methodology for the estimation of different phase volumes in HILIC is presented. For a ZIC-HILIC column mobile volume (hold-up volume) determined several acetonitrile- and methanol-water compositions by Linear Free Energy Relationships (LFER) homologous series approach involving n-alkyl-benzenes, -phenones, -ketones. We demonstrate that works as when contains high medium proportions methanol or acetonitrile. However, acetonitrile contents below 20%, 40% methanol, same RPLC. In between, mixed HILIC-RPLC behavior observed, solutes low molecular are retained mode, but largest ones show RPLC retention. From retention data pycnometric measurements pure organic solvents their mixtures with water, mean solvent composition water-rich transition layers between functionalization bulk phase, which act stationary estimated. Finally, ratio phases also estimated each eluent composition, allowing calculation corresponding volumes. All strongly dependent on water content eluent, especially selected constituent. hydroorganic increases, decrease, (mainly layer adsorbed onto bonded-phase water-enriched interface) increase. at concentrations, where increases (which now bonded zwitterion) decreases increasing percentage phase.