Solvent-generated liquid-liquid chromatography with aqueous ternary systems

Summary

It is shown that solvent-generated liquid-liquid chromatography can also be realized with aqueous ternary systems. One phase of such a liquid-liquid system is used as eluent and the column is packed with a porous solid support whose surface is better wetted by the other phase which is then generated dynamically on it by the mobile phase. The partition mode of retention was verified by linear regression of the chromatographic retention data and the partition coefficients measured at equilibrium. A further confirmation was obtained by the sharp change observed in the retention characteristics when approaching a composition of the mobile phase corresponding to the liquid-liquid equilibrium. The stationary phase is generated rather quickly needing between 10 and 100 times the column volume of mobile phase for equilibration depending on the magnitude of the change of composition of the mobile phase and the specific surface area of the solid support. The stability of solvent-generated LLC columns is very high allowing long term reproducibility of the selectivity coefficient of about 1 %. It is demonstrated that solvent-generated LLC offers a powerful means to optimize the separation of a mixture by chromatography.