Multi-dimensional chromatography is a powerful field of techniques that is rapidly becoming indispensable for the analysis of complex samples. By combining different (or “orthogonal”) separation mechanisms, these techniques allow the sample to be characterized by two or more chemical properties of interest. An emerging example of these techniques is two-dimensional liquid chromatography (2D-LC) where the multi-dimensional hyphenation allows separation modes to be combined with normally incompatible detectors, potentially providing additional sensitivity.
While the essential concepts of 2D-LC were already introduced in the seventies by Erni and Frei  and worked out in 1990 by Jorgenson and Bushey , developments only recently have started to pick up in the last decade or so. There is a clearly identifiable need for 2D-LC for the characterization of complex polymers that feature multiple independent distributions, which created at least one clear driver for developing and improving the technology [3,4]. Because LC×LC offers peak capacities that are about an order of magnitude higher than those attained in conventional one-dimensional LC, the technique was also shown to be advantageous for the separation of very complex mixtures containing 100 analytes or (many) more. For such samples, LC-MS and LC×LC are both relevant technologies. For the detailed analysis of extremely complex samples, LC×LC-MS may ultimately be the way to go.
However, the astounding separation power offered by these techniques comes at a great price. Implementation of 2D-LC in an analytical lab is perceived as too complex and costly, and the analysis of the data as cumbersome. Moreover, many potentially interesting combinations of separation techniques are barely feasible from a technological perspective.
Our research aims to circumvent these issues by
- supplying information and method resources for others to successfully implement the technique
- creating new applications of LC technology to circumvent technological limitations
- developing algorithms to automate and speed-up the cumbersome method development
- constructing tools to enhance the data analysis
Extending the range of multi-dimensional chromatography
One reason limiting the interest in multi-dimensional liquid chromatography is that the additional complexity is detrimental of the multi-dimensional separation is detrimental for the usefulness of the data. For example, in traditional two-dimensional liquid chromatography, the additional separation method dilutes the sample further, resulting in decrease detection sensitivity.
However, recent developments such as the use of shifting gradients and active-modulation techniques have resolved many of these problems. In this branch of research, my team develop applications which combines all of these concepts.
Creative applications of LC technology
In essence, multi-dimensional analytical methods are nothing else than the hyphenation of multiple separation methods with spectroscopic and/or spectrometric techniques. Successful implementations typically limit themselves to the use of techniques. For hyphenation, the used modulation interfaces impose rather detrimental limitations to the overall method.
My team develop separation systems making such analytically incompatible approaches compatible. In this framework, we use the modulation of techniques as opportunity to facilitate compatibility and to increase the potential of the characterization method.