Optimized Use of a 50 μm Internal Diameter Secondary Column in a Comprehensive Two-Dimensional Gas Chromatography System

The focus of the present research is directed toward the development of a comprehensive two-dimensional gas chromatography (GC x GC) method, characterized by a greatly increased separation power, if compared with GC x GC approaches using classical column combinations. The analytical objective was achieved by using a 0.05 mm internal diameter (i.d.) capillary as second dimension, a split-flow approach reported in previous research (Tranchida, P. Q., Casilli, A., Dugo, P., Dugo, G. and Mondello, L. Anal. Chem. 2007, 79, 2266-2275), and a twin-oven GC x GC instrument. The column combination employed was an orthogonal one: an apolar 30 m x 0.25 mm i.d. column was linked, by means of a Y-union, to a flame ionization detector (FID)-connected high-resolution 1 m x 0.05 mm i.d. polar one and to a 0.20 m x 0.05 mm i.d. uncoated capillary segment; the latter was connected to a manually operated split valve, located on top of the second GC. As previously shown, the generation of optimum gas linear velocities in both dimensions can be attained by splitting gas flows at the outlet of the first dimension (Tranchida, P. Q., Casilli, A., Dugo, P., Dugo, G. and Mondello, L. Anal. Chem. 2007, 79, 2266-2275). An optimized GC x GC method was developed and exploited for the analysis of a complex petrochemical sample. The satisfactory results attained were directly compared with those observed using the same instrumentation, equipped with what can be defined as a classical GC x GC split-flow column set: the same primary column was connected to an FID-linked 1 m x 0.10 mm i.d. polar one and to a 0.30 m x 0.10 mm i.d. uncoated capillary. It will be herein illustrated that there is still room for significant progress in the GC x GC field.