Comparison of C18 silica bonded phases selectivity in micellar liquid chromatography.

The paper describes a new test designed in micellar LC (MLC) to compare the commercial C18 stationary phase properties. This test provides the total hydrophobicity, hydrophilicity, steric selectivity, hydrogen bonding, and ion-exchange capacity properties calculation of the ODS stationary phases. Both the test compounds and chromatographic separation conditions choice for column characterization in MLC are detailed. The chromatographic performance of several stationary phases that are used in MLC was evaluated with specific chromatographic test comprising nine test compounds, possessing different physico-chemical properties, which were injected on different supports with two micellar mobile phases: one at pH 7.0 (0.075 mol/L SDS and 1.5% v/v 1-pentanol), and other at pH 2.7 (0.075 mol/L SDS and 1.5% v/v 1-pentanol adjusted to pH by TFA). Fundamental column chromatographic properties were obtained under these conditions and were treated by hierarchical cluster analysis. From the results of cluster analysis, two closely related groups of columns are distinguished, and it was shown that the chosen column characteristic parameters allow characterizing both sorbent and micellar chromatographic system properties. Eleven columns were analyzed by this test, which allows a comparison of columns with the aim of the selection of suitable and analogous column for the analysis with MLC.