REVERSED-PHASE LIQUID-CHROMATOGRAPHIC STUDY OF EXCESS AND ABSOLUTE SORPTION ISOTHERMS OF ACETONITRILE WATER MIXTURES

The retention volumes of the disturbance peak, V(r,(1,2)), and the isotopically labeled counterparts, V(R,1*) and V(R,2*), of the components of acetonitrile-water mixtures were determined over a wide composition range at 25, 35, 45 and 55-degrees-C. An explicit, model-independent, self-consistency equation relating V(R,(1,2)) and the composition derivatives of V(R,1*) and V(R,2*) derived and successfully tested. Also derived were equations that lead to the evaluation (from the same data set) and linkage of the excess and absolute sorption isotherms of the components. The latter isotherms are based on an internally consistent model which permits the determination of the mobile phase volume.