Development of stationary phase gradients and multi-functional stationary phases in capillary formats
Currivan, Sinéad Ann (2012) Development of stationary phase gradients and multi-functional stationary phases in capillary formats. PhD thesis, Dublin City University.
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The following thesis provides an extensive study into the fabrication of polymer monolithic columns in capillary housing, their modification and subsequent characterisation. The fabricated columns, in all instances, were profiles using scanning capacitively coupled contactless conductivity detection (sC4D), a noninvasive method of characterisation, which can provide information on the density of the monolithic column, and the distribution of charged functional groups within the column.
Using thermally initiated co-monomer polymerisation, monolithic columns were fabricated within fused silica capillaries. The resulting distribution of charged functional groups was monitored using sC4D. Thermally initiated gradient monolithic columns produced linear gradients, however, the capacity produced was sufficiently low, as determined by the retention factor, k ( k < 1). Alternatively photo-initiated modification of polymer monoliths was investigated using commercially available optical filters, with a gradient of optical density. However, due to the optical density of the filter, the gradient did not span the desired length of the column.
In the place of a linear gradient, a photo-grafted stepped gradient was produced and characterised using sC4D. The column was successfully applied to the separation of two metal cations. However, the resulting stepped gradient was not ideal for separations. To resolve this problem, an optical filter was developed (in-house). The filter was comprised of commercially available COC films which demonstrated attenuation of UV energy with increasing thickness, resulting in a linear photo-grafted gradient. The column was profiled using sC4D, thus providing a novel, indirect characterisation of the optical filter (complementary to UV/VIS analysis).
Using photo-grafting techniques, a gold nano-particle agglomerated segment of a monolithic column was created. This provided a stationary phase with dualfunctionality, which was applied to the on-line extraction of proteins, followed by reversed-phase chromatography. The columns were characterised using techniques such as field emission SEM and sC4D. This provided a novel application of sC4D.
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