On-Column Visualization of Sample Migration in Liquid Chromatography

Abstract

A quantitative on-column visualization technique for evaluating solute migration in liquid chromatography columns was described. This technique employed a matched refraction index phase system in high-pressure glass columns. In this case, the mobile phase was carbon tetrachloride and the stationary phase was a C18 silica. Because the refractive indexes of the two phases were the same, the column bed, otherwise opaque, was transparent to the eye. Zones of colored solutes could be injected (iodine for instance) and their migration studied along the column. Photographing the sample band during its migration allowed chromatographic information to be extracted using digital technology. As an example of applications for this technique, we show the sample entry through various inlet fittings. The results demonstrate that chromatographers should pay more attention to the selection of inlet frits. Importantly, the frit porosity should be matched to the particle size of the packing.