UNIFAC MODEL AS A HEURISTIC GUIDE FOR ESTIMATING RETENTION IN REVERSED-PHASE LIQUID-CHROMATOGRAPHY

The utility of the UNIFAC activity coefficient determination method fo r understanding the magnitude of solute-solvent interactions in revers ed-phase liquid chromatography (RPLC) is discussed. UNIFAC-computed pa rtition coefficients for the transfer of various homologous series of solutes from aqueous mixtures of methanol, acetonitrile and tetrahydro furan to hexadecane, octane, butane and benzene were used to investiga te the effects of the carbon number, the type of functional group of t he solutes, the composition of the mobile phases, the chain length of alkyl-bonded stationary phases and temperature on retention in reverse d-phase liquid-liquid partition chromatography. Although UNIFAC is not accurate enough to be useful for the quantitative determination of re tention in RPLC, it is useful in explaining a wide variety of issues o f general importance in RPLC.