Comprehensive fraction transfer chromatography

In comprehensive two-dimensional chromatography, time fractions of the first-dimension separation are transferred onto the second-dimension column for a further separation, as explained in previous chapters. Of course, there is no... 

The modulator is the heart of the GCxGC system, and is positioned at the confluence of the coupled chromatography columns. The role of the modulator is to trap or isolate compounds present in a given time fraction eluting from the first-dimension column and reinject these components rapidly into the second column. This essentially yields a time-sampled chromatogram, from the first dimension ( D) to the second dimension ( D). It is critical that the modulator is capable of representatively and faithfully sampling peaks eluting from onto D. This can be achieved by either complete or partial transfer of the first-column eluent, however, both techniques are considered comprehensive. 

LC-LC refers to the conventional two-dimensional mode of chromatography using two full-size separation columns where the fractions from one column are selectively and precisely transferred (online or offline) to one secondary column for a further separation. An LC-LC separation system may be used in either the profiling or targeted mode. The purpose of the profiling mode, also known as comprehensive LC-LC, is to fractionate all components of the analyzed mixture, while the purpose of the targeted LC-LC mode is to isolate either a single or a few specific components (that present similar retention on the first dimension) from a complex mixture. Thus, the transferred volume of the first... 

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