Columns in analytical‐scale supercritical fluid chromatography: From traditional to unconventional chemistries

Abstract

Within this review, we thoroughly explored supercritical fluid chromatography (SFC) columns used across > 3000 papers published from the first study carried out under SFC conditions in 1962 to the end of 2022. We focused on the open tubular capillary, packed capillary, and packed columns, their chemistries, dimensions, and trends in used stationary phases with correlation to their specific interactions, advantages, drawbacks, used instrumentation, and application field. Since the 1990s, packed columns with liquid chromatography and SFC‐dedicated stationary phases for chiral and achiral separation are predominantly used. These stationary phases are based on silica support modified with a wide range of chemical moieties. Moreover, numerous unconventional stationary phases were evaluated, including porous graphitic carbon, titania, zirconia, alumina, liquid crystals, and ionic liquids. The applications of unconventional stationary phases are described in detail as they bring essential findings required for further development of the supercritical fluid chromatography technique.

Advancing Fundamental Understanding of Retention Interactions in Supercritical Fluid Chromatography Using Artificial Neural Networks: Polar Stationary Phases with –OH Moieties

“…Therefore, a small percentage of water in the organic modifier, i.e., 2–5%, could shift the equilibrium toward the free silanols and mitigate the SEF. Thus, the process of regeneration, where the column is washed with a large volume of water, is suggested to reverse the SEF. − However, the SEF phenomenon is still not well understood, and more detailed studies are necessary. Furthermore, organic acids, ammonia, water, and/or buffers can be added to the mobile phase, affecting the separation of acidic/basic analytes and their peak shapes.…”

“…Polar stationary phases with predominant –OH functionalities have been used in more than 35% of published works . At the same time, the –OH functionalities of these phases are more prone to SEF .…”

“…Polar stationary phases with predominant –OH functionalities have been used in more than 35% of published works . At the same time, the –OH functionalities of these phases are more prone to SEF . The well-established linear solvation energy relationship (LSER) classification sorts these columns among the polar stationary phases in two clusters (Supporting Information Figure S1): (i) nonbonded silica and hybrid silica and (ii) polar ligands bonded to the silica surface.…”