Enhanced resolution comprehensive two-dimensional gas chromatography applied to the analysis of roasted coffee volatiles |
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Authors: | Peter Quinto Tranchida Giorgia Purcaro Lanfranco Conte Paola Dugo Giovanni Dugo Luigi Mondello |
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Institution: | 1. Dipartimento Farmaco-chimico, Facoltà di Farmacia, Università di Messina, viale Annunziata, 98168 Messina, Italy;2. Dipartimento di Scienze degli Alimenti, Università degli Studi di Udine, via Sondrio 2, 33100 Udine, Italy;3. Campus-Biomedico, Via Alvaro del Portillo, 21, 00128 Roma, Italy |
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Abstract: | The present research is based on the full exploitation of the separation power of a 0.05 mm internal diameter (ID) capillary, as a comprehensive two-dimensional (2D) GC (GC × GC) secondary column, with the objective of attaining very high-resolution second dimension separations. The aim was achieved by using a split-flow system developed in previous research P.Q. Tranchida, A. Casilli, P. Dugo, G. Dugo, L. Mondello, Anal. Chem. 79 (2007) 2266], and a dual-oven GC × GC instrument. The column combination employed consisted of a polar 30 m × 0.25 mm ID column connected, by means of a T union, to a detector-linked high-resolution 1.1 m × 0.05 mm ID apolar analytical column and to a 0.33 m × 0.05 mm ID retention gap; the latter was connected to a manually operated split valve. As previously demonstrated, the use of a split valve enables the regulation of gas flows through both analytical columns, generating the most appropriate gas linear velocities. Comprehensive 2D GC experiments were carried out on Arabica roasted coffee volatiles (previously extracted by means of solid-phase microextraction) with the split-valve closed (equal to what can be defined as conventional GC × GC) and with the split-valve opened at various degrees. The reasons why it is absolutely not effective to use a 0.05 mm ID column as second dimension in a conventional GC × GC instrument will be discussed and demonstrated. On the contrary, the use of a 0.05 mm ID column as second dimension, under ideal conditions in a split-flow, twin-oven system, will also be illustrated and discussed. |
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Keywords: | Comprehensive two-dimensional gas chromatography GC × GC Flow splitting Roasted coffee Solid-phase microextraction |
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