Introduction to 2DLC

Abstract

Today’s analytical chemists face increasing demands to maximize the number of compounds that can be separated and identified in a single run but peak overlap continues to be a problem in many chromatographic methods. One method that might help to overcome these issues is multidimensional liquid chromatography, which uses two columns of different phases. A sequential collection of aliquots is made from the first column and reinjected onto a second; the resulting data are then plotted in 2D or 3D space. The total peak capacity of such a system is the combined peak capacities of each column. The ‘offline’ version of this technique, using a fraction collector, was introduced over 40 years ago but with recent advances in instrumentation and software, particularly the ‘online’ approach, using automated switching valves, has led to increasing interest in the technique. Both offline and online methods can be carried out as a comprehensive procedure, or via ‘heart-cutting’, in which only specific peaks are analysed in the second dimension. Applications include proteomics, natural product chemistry, forensic science, and pharmaceutical analysis. These successes are likely to be built on in the future as new column chemistries and bio-informatic approaches are developed. In this chapter, an overview of the two-dimensional liquid chromatography is presented to give the reader a basic understanding of this emerging technology and its potential future uses.