Rapid isolation of high solute amounts using an online four-dimensional preparative system: normal phase-liquid chromatography coupled to methyl siloxane-ionic liquid-wax phase gas chromatography.
This study reports the recent evolution of a multidimensional GC-GC-GC preparative system, now combined with an online LC preseparation step, operated under normal phase conditions. It is herein shown that the four-dimensional instrument can collect sample components with a concentration lower than 10%, in a short time period, while maintaining a high level of analyte purity. The LC dimension allows (I) the injection of higher sample amounts, compared to "direct" GC injection; (II) a polarity-based preseparation, leading to the GC injection of simplified subsamples, and thus reducing the possibility of coelutions; (III) to eliminate the essential-oil "matrix", replacing it with the LC mobile phase (the GC system is more protected from potential contamination); (IV) the LC mobile phase is of much lower viscosity with respect to a pure, or highly concentrated essential oil, avoiding difficulties in the syringe sample withdrawal process, prior to GC injection. System optimization was performed by using standard solutions; in addition, a very complex sample, namely, vetiver essential oil, was subjected to the preparative process, with the scope of isolating two low-amount constituents (namely, α-amorphene and β-vetivone). The latter two sesquiterpenoids, which accounted for 1.7 and 4.0% of the sample (considering the volatiles), respectively, were successfully collected at the milligram level, in a one-day work period, with a purity degree in excess of 90%.
Dipartimento di Scienze del Farmaco e dei Prodotti per la Salute, Università di Messina , Viale Annunziata, 98168 Messina, Italy.
Danilo
D
Sciarrone
Sebastiano
S
Pantò
Peter Quinto
PQ
Tranchida
Paola
P
Dugo
Luigi
L
Mondello
D002849:Chromatography, Gas / Q000379:methods*; D002853:Chromatography, Liquid / Q000379:methods*; D052578:Ionic Liquids / Q000737:chemistry*; D012833:Siloxanes / Q000737:chemistry*
D052578:Ionic Liquids; D012833:Siloxanes