**Author details**

Peter Kusch

*Gas Chromatography - Derivatization, Sample Preparation, Application*

mer blends, biopolymers, and natural resins [3].

**2. Multidimensional gas chromatography**

used extensively over the last 30 years as a complementary analytical tool used to characterize the structure of synthetic organic polymers and copolymers, poly-

Developed by Phillips and coworker at the Southern Illinois University (USA) in the early 1990s, comprehensive multidimensional GC (GC × GC or 2D GC) is a powerful technique for samples containing very large numbers of compounds of interest and also for samples which exhibit high chemical complexity. This technique can be used to separate very complex mixtures, such as those found in the petrochemical, environmental, and food and fragrance industries [4–6]. The method uses two capillary columns, typically of very different polarities, installed in series with a modulator in between. The first column is in principle nonpolar or low polar, and the second column is polar. The length of the first column might typically be 20–30 m, the inner diameter 0.25 mm, and the film thickness 0.25 μm. The second column is typically shorter (1–2 m), the inner diameter is narrower (0.1 mm), and the stationary phase is thinner (0.1 μm), to allow for faster separations. The entire assembly is located inside the GC oven [6]. The modulator collects effluent from the first column for a fraction of the time equal to peak width. The modulator focuses the material collected from each cut into a very narrow band through flow compression. It introduces the bands sequentially onto the second column, resulting in additional separation for each band injected onto the second column [4–9]. The most common data transformation is the construction of a 2D representation, in which one axis represents the separation on the first column (first dimension), and the other axis represents the secondary column separation (second dimension). Therefore, the look of GC × GC chromatograms appears completely different from conventional GC chromatogram showing a two-dimensional plane where analyte spots are scattered about [7, 8]. A contour plot, using elevation lines or color coding, represents the signal intensity. 2D GC data are primarily used for

*2D GC plot of a refinery stream boiling at diesel temperature range. The scale indicates the relative signal* 

*intensity. Figure reprinted from Ref. [10] with permission from ACS.*

**4**

**Figure 1.**

Department of Applied Natural Sciences, Bonn-Rhein-Sieg University of Applied Sciences, Rheinbach, Germany

\*Address all correspondence to: ptrkusch@arcor.de

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