The Performance of Packings in High Performance Liquid Chromatography (HPLC) I. Porous and Surface Layered Supports

Abstract

The performance of Porasil®, Corasil®, Corning Porous Glass (CPG), and Zipax® are compared for retained and unretained solutes by comparison of plots of the logarithm of reduced plate height against the logarithm of reduced velocity using 48 micron particles (275/325 mesh); and the type of information which can be obtained from such plots is discussed. Zipax gives the best performance for both retained and unretained solutes. The other three supports give similar plate height curves for retained solutes in both partition and adsorption modes, but Corasil gives the best results for unretained solutes. The higher plate heights and gradients of plots for the porous materials (Porasil and CPG) than for Zipax arise from the necessity of molecules to diffuse through stagnant mobile phase held within the pores of the supports. The higher plate height for Corasil than for Zipax for retained solutes is thought to indicate slow mass transfer within the fine pore structure of the silica gel surface layer. The dependence of plate height upon velocity for the porous materials may be quantitatively interpreted in terms of Giddings' theory for diffusional mass transfer in such materials.