Two-dimensional chromatography
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Two-dimensional chromatography is a type of chromatographic technique in which the injected sample is separated by passing through two different separation stages. This is done is by injecting the eluent from the first column onto a second column. Typically the second column will provide a different separation mechanism, so that bands which are poorly resolved from the first column may be completely separated in the second column. (For instance, a C18 column may be followed by a phenyl column.) Alternately, the two columns might run at different temperatures. The second stage of the separation must be run much faster than the first, since there is still only a single detector.
Two-dimensional separations can be carried out in gas chromatography or liquid chromatography. Various different coupling strategies have been developed to "resample" from the first column into the second.
The chief advantage of two-dimensional techniques is that they offer a huge increase in peak capacity, without requiring extremely efficient separations in either column. (For instance, if the first column offers a peak capacity (k1)of 100 for a 10 minute separation, and the second column offers a peak capacity of 5 (k2) in a 5 second separation, then the combined peak capacity may approach k1 × k1 = 500, with the total separation time still ~ 10 minutes.) 2D separations have been very successfully applied to the analysis of gasoline and other petroleum mixtures, and more recently to protein mixtures. [1] [2].
[edit] References
- ^ Jan Blomberg, Peter J. Schoenmakers, Jan Beens, Robert Tijssen (1997). "Compehensive two-dimensional gas chromatography (GC×GC) and its applicability to the characterization of complex (petrochemical) mixtures". Journal of High Resolution Chromatography 20 (10): 539-544. doi:.
- ^ Stoll, D.R., Wang, X., Carr, P.W. (2008). "Comparison of the practical resolving power of one- and two-dimensional high-performance liquid chromatography analysis of metabolomic samples". Analytical Chemistry 80 (1): 268-278. doi:.
