Download our free whitepaper: Benefits of Comprehensive Two-Dimensional Gas Chromatography (GCxGC) for a Routine Laboratory, authored by Michelle Misselwitz, Chemistry Consultant at Chemistry Matters, Inc., for more information on how GCxGC can benefit your laboratory.
Comprehensive Two-Dimensional Gas Chromatography
LECO GCxGC combined with Electron Capture or Flame Ionization Detectors offer you the resolving power of a GCxGC system combined with our advanced ChromaTOF® software for an increase in efficiency and productivity for samples that are too complex for a single-channel detector system. Ideal for everyday quality control and production needs, these GCxGC systems provide you with all the tools necessary to achieve exceptional results in a cost-effective package.
- Enhanced separating power for complex sample analysis
- Easy-to-use ChromaTOF®-based software provides acquisition processing and reporting funtionality within a single package
- Classification software feature simplifies component identification
- Flame Ionization Detector (FID) and Electron Capture Detector (ECD) models available
- Available Cryogen-free modulator eliminates the need for LN2 dewars
Theory of Operation
In GC analysis, chemical compounds are separated by their interaction with the stationary phase in a GC column. Sometimes, however, the separation is not sufficient to provide identification and/or quantification of all compounds. In many situations involving simple sample analysis, the inability to separate two compounds on a GC column with one stationary phase may be resolved by the use of a different column with a different stationary phase. However, as samples become more complex, the simple substitution of one chromatographic stationary phase for another may result in improvements in separation between some compounds with loss of separation between others. In this situation, the combined separation provided by each of two stationary phases is required. As opposed to limited techniques such as heart-cutting, comprehensive two-dimensional gas chromatography (GCxGC) provides superior chromatographic resolution across the entire sample.
In comprehensive two-dimensional gas chromatography (GCxGC) all of the analyte passes from the first column through the second. Compounds eluting from the first chromatographic column are trapped, and then systematically injected into the second column to obtain the second separation. In order to retain the chromatographic resolution obtained from the first separation, the second orthogonal separation must take place quickly. As such, it is important that compounds be introduced into this column quickly and in a narrow chromatographic band. In the LECO GCxGC system, this is accomplished by cryogenic dual-stage modulation. With cryogenic modulation, compounds eluting from the first chromatographic column are trapped in a narrow zone in the column as it passes through the modulator. When this zone is rapidly heated, the trapped compounds pass into the second chromatographic column as a narrow band, allowing for the highest possible resolution in the second separation.
In order to properly trap and modulate analytes more volatile than n-octane (C8 n-alkane) the lowest achievable modulation temperatures are required. Reaching these low temperatures requires the use of a cryogen such as Liquid Nitrogen (LN2). LECO's LN2 modulator delivers the ability to modulate these volatile analytes. However, the use and management of LN2 dewars in a laboratory can be a hindrance to productivity. The Consumable-Free modulator is, therefore, an excellent choice for laboratories hesitant to take on the management of LN2 dewars and who do not require modulation of volatile analytes.
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GCxGC ECD/FID Details
GCxGC With LN2 Cooled Thermal Modulator
GCxGC With Consumable-Free Modulator
- Liquid Nitrogen, Automated Fill
- Optional Inlets Available (Including S/SL, PTV, And MMI)
- Optional Detectors available (Including FID And ECD)
Quantification of Dioxin-like Polychlorinated Biphenyls [PDF]
GCxGC ECD/FID [PDF]