Phase distribution chromatography. Possibilities and limitations

Abstract

This article reviews the development of a new chromatographic column method, the phase distribution chromatography (PDC). PDC is based on the interaction of an injected diluted solution of a polymer (mobile phase) with a non-crosslinked gel of the same polymer immobilized on the surface of small glass beads. This interaction takes place at a constant temperature below the theta temperature of the system. The observed high resolution of the PDC-column at low temperatures cannot be explained by a reversible-thermodynamical equilibrium as described by the usual partition function K(P). It is rather explained by a new partition function Q(P) of a flow-equilibrium (steady state) for the P-mer transported between sol and gel in the column. The flow-equilibrium itself is explained by means of a deformation of the transported macromolecules, caused by the stress related to the high and steep velocity gradient of the column liquid near the gel front. Since the resolution of a PDC-column vanishes near the theta point of the system, spreading phenomena can be measured exactly in this region. Both properties of the column — the powerful resolution at low column temperatures, and the vanishing of its resolution near the theta point — enable an efficient and exact determination of narrow molecular weight distributions from PDC-measurements. The possibilities of PDC in these three fields (thermodynamics and kinetics of the resolution mechanism, spreading of the injected profile, and determination of the MWD) are demonstrated in detail. Limitations of the new column method are also discussed.