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Abstract
Based on the stoichiometric displacement theory for retention of solute (SDT‐R), the changes of free energy of biopolymers during retention process in reversed‐phase high performance liquid chromatography (RPLC) can be divided into two independent fractions, the adsorption and desorption free energy changes. The totally net free energy change and the two fractions of seven kinds of proteins in RPLC were accurately measured. The standard deviation between experimental values and theoretical expectation was less than ±2%. In addition, from the point of view of thermodynamics, with the comparisons of the adsorption and desorption free energy changes between small solutes and biopolymers in RPLC, the following experimental facts were first explained quantitatively: [Robbat, A., Jr.; Liu, T.Y. J. Chromatagr. 1990, 513, 117] The elution range of organic solvent for small solutes in the mobile phase in RPLC is usually broad, while that for biopolymers is very narrow. [Tan, L.C.; Carr, P.W. J. Chromatogr. 1993, 656, 521] Small solutes in RPLC can be eluted with isocratic elution, but biopolymers only with gradient elution. [Tchapla, A.; Heron, S.; Colin, H.; Guiochon, G. Anal. Chem. 1988, 60, 1443] The resolution of small solutes in RPLC depends on column length, while that of biopolymers is almost independent of it.
Acknowledgments
This work was supported by the National Natural Science Foundation of China (Grant No. 29675017 and 39880003), the Foundation of the Young Teacher in the University of Ministry of Education P. R. C (Grant No. DF00308), and the Foundation of the Committee of Education in Shaanxi Province (Grant No. 99JK101).