Hydrophilic interaction liquid chromatography (HILIC)—a powerful separation technique

Hydrophilic interaction liquid chromatography (HILIC) provides an alternative approach to effectively separate small polar compounds on polar stationary phases. The purpose of this work was to review the options for the characterization of HILIC stationary phases and their applications for separations of polar compounds in complex matrices. The characteristics of the hydrophilic stationary phase may affect and in some cases limit the choices of mobile phase composition, ion strength or buffer pH value available, since mechanisms other than hydrophilic partitioning could potentially occur. Enhancing our understanding of retention behavior in HILIC increases the scope of possible applications of liquid chromatography. One interesting option may also be to use HILIC in orthogonal and/or two-dimensional separations. Bioapplications of HILIC systems are also presented

Characterization of wide-pore reversed-phase columns for biopolymer separations. I. Single-parametric evaluation

Nine prepacked wide-pore columns recommended for protein separation were studied. The stationary phases investigated were widely different with respect to the type of ligands. In order to characterize the columns, measurements were made with six different test mixtures containing two different homologous series, substituted benzenes and amino acids, peptides and proteins. The isopotential eluent compositions obtained for the homologous series revealed the polar-apolar nature of the stationary phases. The relative hydrophobicity calculated for the individual test compounds provided more thorough but still partial characterization. The involvement of substituted benzenes resulted in the most complete description. The characterization with amino acids, peptides and proteins furnished results similar to those obtained for smaller test compounds having low or intermediate polarity. The examination of the behaviour of proteins revealed that the retention is determined by the hydrophobicity of the stationary phases and the other characteristics affect the selectivity