* GCxGC thermal modulator and GC Image are products of Zoex Corporation (United States).
GC×GC chromatography employs a pair of GC columns (generally, nonpolar and polar columns) connected in series through a modulator*. Effluent from the first column is trapped in the modulator for a fixed period of time (modulation time) before being focused and injected into the second column . The chromatograms obtained through repeated trapping and injection is rendered in two dimensions using specialized software*. This result in a two-dimensional chromatogram with the boiling point and polarity on the respective axes.
* GC×GC Modulator and GC Image are products of Zoex Corporation, USA.
MDGC uses two columns with different separation characteristics for highly accurate separation of target components from a complex matrix.
Introduction to Applications
Data on this page was provided by the group run by Professor Luigi Mondello, University of Messina, Italy.
An interview with Professor Mondello is featured in our section, A bridge with our customers.http://www.shimadzu.com/an/bridge/brigde7.html
Analysis of Mate Tea
Mate tea is widely consumed in the countries of South America as a tonic and stimulating beverage to overcome fatigue. We performed GC×GC analysis of the volatile components in a mate tea beverage (Ilex paraguariensis leaves and twigs) purchased in the Brazilian market.
GC×GC-qMS Chromatogram of Mate Tea
(First column: SLB-5ms (L=30 m, I.D.=0.25 mm, df=0.25 μm); Second column: Equity 1701(L=1.5 m, I.D.=0.1 mm, df=0.1 μm), modulation time 6 s)
The first column is a micropolar column and the second column is a mid-polarity column with dimensions suitable for fast analysis. An extremely large number of components were detected in the 2D chromatogram obtained. Hydrocarbon group components were detected in the lower part of the 2D diagram (low-polarity region). Caffeine was also detected as a prominent compound.
A library search using the mass spectrum identified 241 of the over 1000 peaks detected. It is apparent that GC×GC is an effective means of analyzing complex samples.
GC×GC-qMS Chromatogram of Mate Tea and Identification Results
This application data was provided by the group run by Professor Luigi Mondello, (University of Messina, Italy and Chromaleont S.r.l)
Fatty Acids in Blood Plasma
Fats in foods are attracting attention due to their deep relationship to a series of diseases including hypertension, heart disease, obesity, and hypercholesterolemia. They have been widely researched using chromatography in recent years. However, conventional methods suffer from several problems: 1) inability to identify the double-bond position in fatty acid isomers due to the similarity of the mass spectra, 2) poor GC resolution, and 3) inability to detect trace peaks due to poor sensitivity. In this example,a high-resolution, high-sensitivity GC×GC method was applied to the determination of fatty acid methyl esters in human blood plasma.
2D Chromatogram of Fatty Acid Methyl Esters in Blood Plasma
（First column：SLB-5ms（L=30m, i.d.=0.25mm, df=0.25μm), Second column：Supercowax-10（L=0.95m, i.d.=0.1mm, df=0.1μm), modulation time：6sec)
It is apparent that the FAME peaks corresponding to the carbon number (C), double bond number (DB), and double bond position (ω) are regularly distributed on the 2D chromatogram. This spatial distribution arrangement is extremely effective for the identification of compounds. Of the 65 peaks, 29 could be identified based on this arrangement. (The peaks labeled (st) in the diagram result from standard samples.) In addition, low levels of fatty acids with odd carbon numbers were also detected.
This application data was provided by the group run by Professor Luigi Mondello, (University of Messina, Italy and Chromaleont S.r.)
Analysis of Coffee
The aroma of roasted coffee is characterized by the presence of several thousand types of volatile compounds, mainly belonging to the pyran, pyrazine, and pyrrole group. The olfactory sensitivity, concentration, and chemical characteristics differ from type to type and the mutual interactions between them determine the characteristic aroma of the coffee. We used GCGC-MS to analyze the volatile components in coffee beans that are hard to analyze by conventional GC due to their extremely complex compositions.
2D Chromatogram of the Volatile Components in Arabica Coffee
（L=30m, i.d.=0.25mm, df=0.25μm), Second column：SPB-5ms（L=1.0m, i.d.=0.1mm, df=0.1μm), modulation time：6sec)
A polar-nonpolar column pair was used for this analysis. Several thousand peaks on the two-dimensional plane,and we obtained a good plot of the extremely complex coffee aroma.
Pyrazine Groups Visualized on the 2D Chromatogram
It is apparent that 14 types from the pyrazine group form according to the side-chain carbon number and are aligned as horizontal bands.
This application data was provided by the group run by Professor Luigi Mondello, University of Messina, Italy