Model-independent aspects of tracer chromatography theory

Abstract

A theory of tracer chromatography is developed on the basis of population balances in the steady state. As well as to tracer systems the theory applies to chromatography with a carrier gas if the system response is linear. It is shown that the time of passage of a tracer peak can properly be taken to be the mean residence time of the tracer and that the mean time is directly related to thermodynamic properties. Many results of chromatography theory may be established easily without the need for the assumptions usually employed. Thus the methods already developed for the chromatographic determination of thermodynamic properties are more powerful, and there is more freedom in the design of experiments, than had been realized. The mean residence time of species i in the steady state is equal to the ratio of the holdup of i in the system to the rate of transmission of i through the system. By invoking the hypothesis that in the steady state the system is in equilibrium with its feed, the mean time can be related to thermodynamic properties contained in an expression for the holdup. This provides a powerful strategy for developing theoretical results without the need for a mathematical model of the chromatographic process.