Characterization of stationary phases by a linear solvation energy relationship utilizing supercritical fluid chromatography

Abstract

Supercritical fluid chromatography was utilized in combination with the Abraham model of linear solvation energy relationship to characterize 11 different HPLC stationary phases. System constants were determined at one supercritical fluid chromatography condition for each stationary phase. The results indicate that several types of silica columns, including type B silica, type C silica, and fused core silica, are very similar in their retention behavior. Several aromatic stationary phases were characterized and it was found that, in contrast to the other phases studied, all of the aromatic stationary phases had positive contributions from the dispersion/cavity (v) term of the linear solvation energy relationship. Several aliphatic phases were characterized and there were several linear solvation energy relationship constants that differentiated the phases from each other, mainly the polar terms (dipolarity and hydrogen bonding). One stationary phase, a fused core pentafluorophenyl (PFP) phase, had very poor regression quality. The column volume of this phase was lower than the others in the study, which may have had some impact on the results of the regression.

Evaluation of an amide‐based stationary phase for supercritical fluid chromatography

“…The LSER model was constructed using 24, 22, 22, and 21 different solutes varying in polarity for the C 18 , silica, terminal‐amide, and C 18 ‐amide, respectively. The solutes and the descriptors used in the LSER model are presented in Table , which are readily available in the published literature . Three injections were performed for each solute and the average retention factor was used to construct the LSER model from which the system constants were extracted.…”

“…The linear solvation energy relationship (LSER) model using Abraham descriptors has acquired favorable acceptance in SFC to characterize column selectivity . This model has been used to rationalize the intermolecular processes that lead to the separation of solutes.…”

“…These solute descriptors are obtained by TripleX, Solver, Descfit, or Regression programs . These descriptors are readily available in the literature . The system constants relate to the different chromatographic interactions, extracted by multiple linear regression analysis, for a particular chromatographic system and are defined as follows .…”

“…These descriptors are readily available in the literature . The system constants relate to the different chromatographic interactions, extracted by multiple linear regression analysis, for a particular chromatographic system and are defined as follows . The e parameter represents the interactions through nonbonding pi and n‐electron pairs; the s term measures the system ability to interact by dipole–dipole interactions; the a term is a measure of the ability to donate a lone pair of electrons or accept H‐bond (system basicity); b measures the ability to accept a lone pair of electrons or donate H‐bond (system acidity); v measures the hydrophobic interaction between the mobile phase and the stationary phase; and c is the model intercept term.…”

“…A large inventory of chromatographic columns has been characterized by LSER under SFC conditions. However, new stationary phases are introduced and their characterization and comparison with existing ones is meritorious.…”