title: Use of limonene in countercurrent chromatography: a green alkane substitute.
abstract: Counter-current chromatography (CCC) is a preparative separation technique working with the two liquid phases of a biphasic liquid system. One phase is used as the mobile phase when the other, the stationary phase, is held in place by centrifugal fields. Limonene is a biorenewable cycloterpene solvent coming from orange peel waste. It was evaluated as a possible substitute for heptane in CCC separations. The limonene/methanol/water and heptane/methanol/water phase diagrams are very similar at room temperature. The double bonds of the limonene molecule allows for possible π-π interactions with solutes rendering limonene slightly more polar than heptane giving small differences in solute partition coefficients in the two systems. The 24% higher limonene density is a difference with heptane that has major consequences in CCC. The polar and apolar phases of the limonene/methanol/water 10/9/1 v/v have -0.025 g/cm(3) density difference (lower limonene phase) compared to +0.132 g/cm(3) with heptane (upper heptane phase). This precludes the use of this limonene system with hydrodynamic CCC columns that need significant density difference to retain a liquid stationary phase. It is an advantage with hydrostatic CCC columns because density difference is related to the working pressure drop: limonene allows one to work with high centrifugal fields and moderate pressure drop. Limonene has the capability to be a "green" alternative to petroleum-based solvents in CCC applications.
authors.affiliation: Institut des Sciences Analytiques, CNRS, Université de Lyon, Villeurbanne, France.
authors.forename: Karine
authors.initials: K
authors.lastname: Faure
authors.forename: Elodie
authors.initials: E
authors.lastname: Bouju
authors.forename: Pauline
authors.initials: P
authors.lastname: Suchet
authors.forename: Alain
authors.initials: A
authors.lastname: Berthod
mesh_terms: D000473:Alkanes / Q000737:chemistry*; D003377:Countercurrent Distribution; D053138:Cyclohexenes / Q000737:chemistry*; D057446:Hydrodynamics; D000077222:Limonene; D000432:Methanol / Q000737:chemistry; D015394:Molecular Structure; D013729:Terpenes / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D000473:Alkanes; D053138:Cyclohexenes; D013729:Terpenes; D014867:Water; D000077222:Limonene; D000432:Methanol