Separation of polar compounds by solvating gas chromatography with carbon dioxide mobile phase

Abstract

SummaryIn this study, the separation of polar compounds in solvating gas chromatography (SGC) was investigated. Capillary columns (250 gm i.d.) packed with deactivated siliceous particles, including SE-54 encapsulated silica particles, diol-bonded silica particles, and polyethylenimine (PEI) coated particles, and nonsiliceous particles of styrene-divinylbenzene were used. Polar compounds that were used as test solutes included ketones, aldehydes, esters, nitro-containing compounds, alcohols, phenols, fatty acids, and amines. It was found that capillary columns packed with SE-54 encapsulated particles were suitable for the separation of medium polar compounds, columns packed with diol bonded silica particles could be used for separation of strongly polar compounds such as fatty acids, and columns packed with PEI coated silica particles were suitable for the separation of basic compounds such as alkylamines under SGC conditions. Columns containing the polymeric particles could be used for the separation of medium polar compounds and weak bases, however, low column efficiency was observed. SGC was found to provide better separation of polar compounds than high pressure gas chromatography (HPGC). A sample of a peppermint oil was separated within 8 min under SGC conditions.

Strategy for Selection of Composite Membrane Materials

“…Slater and co-workers tried to use a silicone composite membrane to separate methyl ethyl ketone from ethanol, but with little success. In addition, many nonmembrane methods, such as solution-phase complexation, chromatography, and supercritical fluid gas chromatography, have been used to separate ketones, alcohols, and hydrocarbons on a laboratory scale.…”

Peak capacity in packed capillary column solvating gas chromatography

“…Compared with "brush" structure bonded phases, hydrosiloxane polymer-encapsulated particles provide a more inert surface which is suitable for the separation of polar compounds, even when using weakly polar CO 2 as the mobile phase [7,9]. In this study, the separation capabilities of these particles were examined using normal hydrocarbons as test solutes, and the results are illustrated in Figure 3.…”

“…In SGC, the mobile phase can change from a supercritical fluid to a gas [4] or from a superheated liquid to a gas [5], or remain as a solvating gas [6] throughout the column length. Both adsorbents [6] and bonded phases [7] have been used in SGC to perform solvating gas-solid chromatography (SGSC) and solvating gasliquid chromatography (SGLC). An analysis of the peak capacities indicated that packed column SGC provided similar separation capability to open tubular column gas chromatography [3].…”

Packed Capillary Column Solvating Gas Chromatography Using Mobile Phases That Transition from Liquid to Gas between the Column Inlet and Outlet

“…Previous studies have shown that solvating gas chromatography (SGC) provides high-speed 1 and high-efficiency separations 2 and is even suitable for the separation of polar compounds such as free acids and amines 3 when using microparticle packed capillary columns and CO 2 as mobile phase. When CO 2 is used as the mobile phase, the column inlet and outlet behave as supercritical fluid chromatography (SFC) and gas chromatography (GC), respectively.…”