Relative Average Mass Transport Properties of Mixture Components in the Presence of a Porous Silica Gel Depend on the Solution/Solid Phase Ratio

In this work, we followed by pulsed-field gradient (PFG) NMR the evolution of the value of the average diffusion coefficient for molecules in a mixture in the presence of silica gel of chromatographic grade for variable solution/solid ratios. This analysis revealed a dramatic change, along the series of experiments, in the differences of the apparent diffusion coefficients of the mixture components, which determines the facility of separation. Notable consequences of this variation is that an effective separation is predicted to be possible in conditions that are specific to a mixture/solid phase combination and that agreement with column LC can be achieved only under certain conditions.