Thermodynamic nonideality and the dependence of partition coefficient upon solute concentration in exclusion chromatography. Application to self-associating and non-self-associating solutes. Application to hemoglobin.

The theory of partition of macromolecular solute between mobile and stationary phases under highly nonideal conditions is reexamined. Expressions are derived for the dependence of the partition coefficient of a non-self-associating solute, and the weight average partition coefficient of a dimerizing solute, upon the total concentration of solute in the mobile phase. These expressions are based upon a treatment of nonideality in the stationary phase which is more realistic than that proposed earlier [L.W. Nichol, R.J. Siezin and D.J. Winzor, Biophys. Chem. 9 (1979) 17]. It is found that the chromatographic data on oxyhemoglobin in the above paper may be accommodated by the present theory without invoking self-association.