Comparison of acitvity coefficients measured by a static and by a dynamic method

Abstract

Activity coefficients at infinite dilution were determined for various chlorinated hydrocarbons in squalene and dinonyl phthalate by two distinct chromatographic methods. The first, and well known method, involved the measurement of specific retention volumes; the second, and less common method, involved measurements obtained from the diffuse edge of a single chromatographic peak. In the latter case the injection of very large samples was necessary. The results are compared with activity coefficients obtained by the static method that uses a McBain balance. Generally, agreement between the dynamic and static methods is good. A conclusion reached is that non-linearity of the partition isotherm may be an important factor when measuring activity coefficients even at infinite dilution.