Index
Multidimensional Chromatography
Multidimensional systems require three main parameters:
1. Each dimension should separate according to different physical or chemical properties
2. There must be an efficient means of interfacing the (two) separation modes
3. The two separation modes must be compatible
GCxGC
Our group concentrates on Comprehensive Multidimensional Gas Chromatography (GCxGC) using the Longitudinal Modulated Cryogenic System (LMCS) to couple the two selected chromatography columns. The LMCS (pictured below), designed and developed by Prof Philip Marriott at RMIT, ensures the complete transfer of solute from column 1 to column 2 such that the individual separation on each column is preserved, and orthogonal separation is achieved.
The LMCS
A picture of the cryogenic modulation system, which is used in the RMIT lab to give the ultra-high resolution technique of comprehensive multidimensional gas
The GCxGC Setup
LCxLC
Multidimensional Liquid Chromatography is also being investigated by our group. This technique has been used for a long time using techniques such as heart-cutting or comprehensive liquid chromatography. In heart-cutting chromatography, a portion of the effluent is transferred to a second dimension in order to separate unresolved compounds from the first dimension. However, in comprehensive liquid chromatography, the whole first column effluent is analysed through a second dimension. Recent advances towards increasing peak capacity and gaining greater resolution and increased peak capacity through column switching are being studied in micro HPLC. Following technologies developed using cryotrapping in GCxGC, a cryogenic trapping system is being designed in liquid chromatography whereby a cold region is created to focus and concentrate solutes in a narrow portion of tubing after a first dimension analysis. The concentrated solutes are subsequently rapidly analysed by a different separation mechanism by a second column with a different stationary and mobile phase.