Two-dimensional HPLC (2-D HPLC) facilitates the separation of complex mixtures by using different chromatography modes as sequential steps. 

There are important advantages in operating the first dimension in displacement mode.  First, owing to the concentrating effect of displacement chromatography, one observes many more small peaks that are otherwise undetected in ordinary HPLC analyses.  Furthermore, small impurity peaks that run close to the main components are much more easily observed and measured owing to  the concentrating effect noted earlier and because most of the main component peak is removed from this region of the analysis.  

A third dimension can be conveniently added to the system by putting a mass spec detector at the end of the second HPLC column.   A mass spec detector provides an additional dimension of separation and allows one to identify the chemical structure of each peak. 

2-D HPLC can can be especially useful in:

• Process analysis and control
• Quality by Design (QbD) Programs
• Proteomics
• Product Analyses
• DNA fragments
• Proteins and peptides

Learn more about 2-D HPLC:

Improving Process Analysis & Control Using Displacement Chromatography As a First Step in 2- or 3-Dimensional HPLC Analyses (dLC x eLC)