On-line multidimensional LC-techniques. Determination of known and unknown compounds in limited and complex samples
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Thesis defended Desember 2007.
The work presented in this thesis deals with instrumental-and method development of various multidimensional on-line liquid chromatography-solid phase extraction-spectroscopy combinations and applications performed utilizing such instrumentation.
Reasons for employing on-line instrumentations are, amongst others, the possibility of automation with a lowered risk of human error and greater lab throughput, and the increased ability to handle small sample sizes and low analyte concentrations.
Liquid Chromatography (LC)-based on-line systems (i.e. on-line LC-NMR or on-line two dimensional (2D LC)) are available without Solid Phase Extraction (SPE) columns incorporated in the system. However, employing SPE columns have many benefits, such as enabling large volume injections on capillary LC (cap LC) columns, aiding the separation of very large amounts of compounds with conventional HPLC columns and eliminating inter-dimension solvent incompatibility in 2D LC systems.
In this thesis it is argued that on-line LC-SPE combinations are well suited tools for solving several key problematic situations encountered in chromatography; when the target compound(s) is often present at very low concentrations in a small sample, and is hence not easy to detect, when the compound(s) of interest must often be separated from the other compounds present, and when the identity of target compound(s) in a mixture is unknown.