Towards greater selectivity and peak capacities in multidimensional separations of complex samples

In this thesis, the focus was on understanding recent developments in liquid chromatography (LC) and how these can be applied to improve two-dimensional separations (Chapter 2). The main advances that were of interest for the design of a 3D separation device were those in column technology, instrument capabilities and miniaturized separation devices. We proceeded with an investigation into the miniaturization of comprehensive two-dimensional LC (LC×LC) for the analysis of peptides by direct coupling with a high-resolution mass spectrometer (HR-MS) (Chapter 4). In choosing the best combination of retention mechanisms for the LC×LC system, we have investigated computational programs for the prediction of retention and the optimization of peptide separations in hydrophilic-interaction liquid chromatography (HILIC) and reversed-phase liquid chromatography (RPLC) (Chapter 3). Finally, we investigated the introduction of particles in a 3D-printed device as a model for a future 3D-spatial-separation device (Chapter 5). To reach the ultimate goal of a 3D-spatial-separation device with the capability of achieving a peak capacity of one million, further research is still required. The future outlook following the research in this thesis is described in Chapter 6.