Characterization of polyaniline‐coated stationary phases by using the linear solvation energy relationship in the hydrophilic interaction liquid chromatography mode using capillary liquid chromatography

Abstract

A polyaniline coating was used to modify the surface of bare silica gel and octadecyl silica stationary phases to characterize the properties of altered materials. It was assumed that the mixed-mode retention was established on the basis of the polyaniline chemical structure and its combination with the original sorbents. Polyaniline was deposited onto the original surfaces during the chemical polymerization of aniline hydrochloride. The prepared materials were slurry packed into capillary columns and systematic chromatographic characterization was performed using the linear solvation energy relationship, also employing descriptors that allow inclusion of ionic interactions in the proposed retention mechanism. The retention times of 80 solutes with various chemical structures were measured in the hydrophilic interaction liquid chromatography mode. The obtained results demonstrated the significant contribution of the polyaniline coating to the retention mechanism under the given conditions; the assumed mixed-mode retention was confirmed. The dominant retention interaction for both modified stationary phases was based on the protonation of nitrogen atoms in the polyaniline structure, leading to suitable retention and selectivity for the hydrophilic analytes, especially anionic and zwitterionic species. Thus, especially, the polyaniline-coated bare silica gel sorbent seems to be promising for potential applications related to the separation of polar compounds.

Protonation of polyaniline‐coated silica stationary phase affects the retention behavior of neutral hydrophobic solutes in reversed‐phase capillary liquid chromatography

“…This result supports our previous conclusions, suggesting that PANI‐SiO 2 acts as a unique, tunable, mixed‐mode stationary phase (for more information, see Supporting Information Figure S3). In a similar study on the LSER characterization of PANI‐SiO 2 in HILIC mode, the v coefficient was highly negative (albeit using a different mobile phase) .…”

“…PANI‐SiO 2 stationary phase was prepared by in situ chemical polymerization of aniline hydrochloride using ammonium persulfate as a reaction initiator. A detailed description of the sorbent preparation can be found in our previous article . The thickness of the PANI layer on silica substrate was estimated to be 0.2 μm (measured by TEM, see Supporting Information Figure S1).…”

“…In our recent studies, we extended the knowledge on the chromatographic behavior of PANI‐SiO 2 . We described PANI‐SiO 2 as the stationary phase of the mixed‐mode retention mechanism for various solutes in HILIC using the LSER approach . Then, we studied the PANI‐SiO 2 potential to separate structural analogues of either slightly hydrophilic or slightly hydrophobic solutes, in different chromatographic modes, and the changes in the elution order of structurally related solutes based on the variable portion of the organic modifier and on the eluent pH .…”

Recent advances in mixed‐mode chromatographic stationary phases

“…Taraba et al. coated the surface of bare silica gel and octadecyl silica particles with a polyaniline layer . Both stationary phases were packed into capillary columns and characterized using the LSER.…”