The competitiveness of solvent adsorption on polar‐embedded stationary phases

Abstract

Solvation processes on polar embedded stationary phases were investigated by determination of excess isotherms in binary acetonitrile/water mobile phase. The obtained results indicate the competitiveness of acetonitrile and water adsorption on heterogeneous surfaces of chemically bonded stationary phases. The calculation of excess isotherm as a volume of excessively accumulated solvent confirms the competitiveness of solvents' adsorption in qualitative and quantitative meaning. Corresponding excess isotherms of water and acetonitrile are symmetrical with respect to the x‐axis. It confirms that the displaced volume of acetonitrile is replaced by an equal volume of water and vice versa. Additionally, fitting the two‐site adsorption model to experimental data provides quantitative values with low experimental errors. The obtained results confirm the advantage of volumetric assumption of excess adsorption over direct adsorption layers of solvents, which is commonly postulated.

Retention Behavior of Various Aromatic Compounds on Poly(butylene terephthalate) Stationary Phase in Liquid Chromatography

“…As majority of the LC separations are carried out using a reversed-phase condition [9], development of chemically modified silica stationary phase is regarded as a key step for improving the separation of complex sample matrices consisted of many components [9][10][11][12][13][14].…”

Phosphodiester Stationary Phases as Universal Chromatographic Materials for Separation in RP LC, HILIC, and Pure Aqueous Mobile Phase

“…They can be bonded at the stage of secondary silanization (polar-end-capped), embedded between the silica surface and the hydrophobic group (polar-embedded), or attached to the end of the non-polar group (polar-headed) [13][14][15][16]. They exhibit a mixed retention mechanism and can work at high organic modifier content separating polar compounds in HILIC and at high water content separating non-polar compounds in RP [17][18][19][20][21][22].…”

Effect of pH and mobile phase additives on the chromatographic behaviour of an amide‐embedded stationary phase: Cyanocobalamin and its diaminemonochloro‐platinum(II) conjugate as a case study

“…The analytical challenge posed by the LC separation of these two analytes has been recently tackled in our laboratory using RP‐LC based either on a classical octadecyl (C18) bonded to silica stationary phase (ODS) or on a phase belonging to the group of “polar‐embedded” ones . Polar‐embedded phases are characterized by the presence, within the alkyl chain, of a polar functional group, such as an amide, urea or carbamate , in the case of commercial phases, whereas imidazolium , diol‐ester‐phenyl, amine‐P‐C18 (d), phenyl‐amine, and amine are mostly home‐made chemically‐bonded phases. Different mechanisms, like those based on hydrophobic, electrostatic, π–π and hydrogen bonding interactions, as well as on shape and planarity recognition, can be invoked for polar‐embedded phases.…”