The formation, modification and characterisation of monolithic ion exchangers for separation science
Gillespie, Eoin (2009) The formation, modification and characterisation of monolithic ion exchangers for separation science. PhD thesis, Dublin City University.
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Studies into the formation, surface modification, and physical characterisation of silica and polymer-based monolithic phases for separation science are presented.
The application of capacitively contactless conductivity detection (C4D) to capillary ion chromatography and the characterisation of the above modified capillary stationary phases have been investigated. The non-contact character of C4D allows the placement of the detector directly onto the separation column. The characterisation of the behaviour of C4D with variations in eluents and detection position (both on- and off- column) has been shown. The detection of nions and cations using surfactant coated capillary monolithic columns shows C4D to both a sensitive detector on-column and also the removal of extra-column band broadening due to off-column detector placement. The characterisation of novel
stationary phases has generally relied upon the use of destructive or indirect methods to date (i.e. SEM or chromatographic performance); however, the use of C4D allows for the characterisation in both a spatial and a temporal manner. The coating of surfactant onto reversed-phase monolithic stationary phases is characterised in detail, with C4D permitting the visualisation of the removal of excess surfactant. The modification of such modified stationary phases by organic solvent to create stationary phase gradients has also been shown. Investigations into the physio-chemical properties of stationary phases using C4D is documented with a counter ion study. The application of C4D to the characterisation of
photografted polymeric capillary monoliths is shown, with the ability to spatially locate such photografted zones. The relationship of C4D response with regard to the amount of energy used to initiate the photograft lends this technique as an aid in the optimisation of photografting methods. The application of C4D to columns of larger diameters showed an equivalent performance to that of a commercial capillary C4D cell. The ability to scale up C4D will open new avenues for this detection technique in the characterisation of columns in a variety of dimensions
other than capillary scale.
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