Fast supercritical fluid chromatography hydrocarbon group-type separations of diesel fuels using packed and monolithic columns

Abstract

Two approaches for decreasing diesel hydrocarbon group-type separation times by normal phase supercritical fluid chromatography (SFC) are compared. Short (10-15 cm) columns with small 3 microm diameter packing are compared with monolithic Chromolith bare silica columns under high carbon dioxide flow rates approaching 5 ml min(-1). Elution times are reduced up to 13-fold on a 10 cm Chromolith column and 7-fold on the short packed columns compared with conventional length columns run at typical flow rates. Short packed columns, with their higher surface area and retention characteristics, offer higher resolutions compared with Chromolith columns. Diesel samples are separated into saturates, mono-, di-, tri-, and polyaromatics in as little as 2 min on a 10 cm packed silica column. Diesel group-type results on a 15 cm titania-silica coupled column compare favorably with results from longer columns.

Thermoresponsive Polymer Brush on Monolithic-Silica-Rod for the High-Speed Separation of Bioactive Compounds

“…On the contrary, in the fields of analytical science, monolithic silica-rod columns have attracted attention as a new chromatographic support, an alternative to silica beads packed column. − Monolithic silica-rod column is a single piece of silica rod having a three-dimensionally interconnected skeleton structure, which provides through-pores to the column. The three-dimensional (3D) skeleton structure and large through-pores reduce the diffusion path length and flow resistance, leading to a higher column efficiency and column permeability, compared to conventional particle-packed columns .…”

Applications of monolithic columns in gas chromatography and supercritical fluid chromatography

“…Until now, there are very few reported applications of monolithic columns in SFC. Similarly to HPLC, faster elution is achieved with monolithic in comparison to particle packed columns and this further enhances the high‐speed SFC analysis. However, this can be met with the undesirable decrease in resolution.…”

“…This method utilizes a particle packed bare silica column and pure supercritical carbon dioxide as the mobile phase. Paproski et al compared performance of short silica (10 cm) and titania-silica coupled columns (15 cm) packed with 3 μm particles, as well as a silica monolithic column (10 cm) for hydrocarbon group-type separations in Synfuel diesel, commercial diesel, and blending feedstock [72]. Comparison was also made with a conventional 5 μm particle packed silica column (25 cm).…”

Monolithic Poly(styrene-co-divinylbenzene) Columns for Supercritical Fluid Chromatography–Mass Spectrometry Analysis of Polypeptide

“…Since the introduction of polymer-based and silica-based monolithic stationary phases in the early 1990s, − numerous reports concerned their applications in a variety of chromatographic techniques including HPLC, , gas chromatography (GC), , and thin layer chromatography (TLC). , In contrast, applications of monoliths in SFC are scarce despite their significantly reduced flow resistance that can enable the use of higher flow rates . So far, only silica-based monolithic columns were used for the separations strictly restricted to small molecules such as cis/trans β-carotene, carotenoids, diesel fuels, pharmaceuticals, polyprenols, and racemic mixtures . These studies featured shorter SFC analysis times compared to the separations using particle-packed columns but not necessarily a better resolution.…”

“…28,29 In contrast, applications of monoliths in SFC are scarce despite their significantly reduced flow resistance that can enable the use of higher flow rates. 30 So far, only silica-based monolithic columns were used for the separations strictly restricted to small molecules such as cis/trans β-carotene, 31 diesel fuels, 33 pharmaceuticals, 34 polyprenols, 35 and racemic mixtures. 36 These studies featured shorter SFC analysis times compared to the separations using particle-packed columns but not necessarily a better resolution.…”