Separation science is a multi‐faceted discipline, underpinning almost all other fields of science and technology. Its scope encompasses fundamental and cutting edge processes and technologies, based upon exploitation of the physical distribution of chemical and biochemical species between solid, liquid or gaseous ‘phases’, facilitating their separation, purification, and analysis. Separation science plays a particularly pivotal element within the majority of modern analytical methods, methods which continue to support all manner of cutting edge scientific endeavour, including, for example, the current ‘‐Omics’ scientific revolution. As inferred above, separation science can of course vary considerably in physical form and scale, from micro‐extraction, to bench‐top chromatographic methods, to large scale industrial process isolation and preparative systems. However, in each and every case there exists several common factors governing success, perhaps the most significant of which is so‐called ‘phase selectivity’, or the fundamental chemical and biochemical interaction between a molecularly defined/controlled surface or phase, and the individual target or group of molecules.

Applications taking advantage of fluorine-fluorine interactions for separations are a recent analytical trend, with benefits in terms of cost, ease of use and specificity cited as advantages of these so-called “fluorous” techniques. While most current fluorous separations employ columns packed with microspheres, columns based on entrapped microspheres, porous polymer monoliths (PPMs) and open tubes all represent viable alternatives to conventional packed capillaries. In this thesis, the design, optimization and implementation of fluorous stationary phases based on all three of these new technologies are explored. Development of methods and techniques using these systems are presented, with factors affecting their performance being examined. Doing this, the specificity of the fluorous interaction can also be explored, and potential applications for these new materials can be discussed. For the work with entrapped microspheres, the columns that were formed did not prove to have an advantage over those that were unentrapped. Although affixing spheres within a matrix is known to have benefits in terms of bed stability over repeated use, the inclusion of a polymer coating proved to represent a greater concern for the availability of the bead-based stationary phases. Layers of polymer forming over the surface were shown to limit the access of analytes to the entrapped microspheres, restricting the usefulness of these materials. The work with fluorous monoliths proved the most successful, providing clear evidence of improved selectivity when compared to analogs made without fluorination. Fluorous retention specificity was also effectively examined, with secondary effects probed and compared to those that had been discussed for commercially-available fluorous microspheres. Results showed that the monoliths were very much in-line with what had already been seen for sphere-based systems, with residual substrate character providing only a slight contribution to the observed separations. Finally, development of open-tubular columns based on microstructured optical fibers was the most speculative of the projects discussed here. The introduction of a fluorous stationary phase through silanization was demonstrated to be an effective method for imparting chromatographic selectivity into these columns, and controllable factors such as treatment protocol and silane character were shown to affect the performance of the resulting materials. / Thesis (Ph.D, Chemistry) -- Queen's University, 2011-05-06 17:03:14.803

In this research project, systematic studies of polymer-assisted flocculation and dewatering behaviour of colloidal gibbsite (y-Al(OH)3) dispersions, together with polymeric flocculant structure-mediated interfacial chemistry and particle interactions, have been performed. Clear links between flocculation performance, interfacial chemistry, particle interactions, dispersion settling rate and sediment consolidation were established for improved dewaterability.

In this research project, systematic studies of polymer-assisted flocculation and dewatering behaviour of colloidal gibbsite (y-Al(OH)3) dispersions, together with polymeric flocculant structure-mediated interfacial chemistry and particle interactions, have been performed. Clear links between flocculation performance, interfacial chemistry, particle interactions, dispersion settling rate and sediment consolidation were established for improved dewaterability.

No description available.

No description available.

The advent of microfluidic technology presents many difficulties but also many opportunities for separation science. Leveraging the potential of micro- and nanofluidic geometries is not only a matter of shrinking systems. Miniaturization can shift the relative importance of physical phenomena leading to separation. Theoretical and computational studies into the consequences of miniaturization are vital. Mesoscopic, multi-particle collision dynamics simulations are performed on polyelectrolytes and hard, colloidal solutes. Multiple variations of this simulation algorithm are implemented to achieve versatility for simulating non-equilibrium flows and dispersed solutes. The algorithm is extended to simulate the effects of finite Debye layers on the electro-hydrodynamics of electrophoresing macromolecules and used to study the electrophoresis of charged oligomers, polyelectrolytes and polyampholytes in both free-solution and confined geometries. Multi-particle collision dynamics simulations of hydrodynamic chromatography and field-flow fractionation are also performed to test the predictions of the derived unified, ideal retention theory. This unified, ideal retention predicts the transitions between multiple operational modes, including Faxén-mode FFF. Simulations and the theory show that increases in drag due to hydrodynamic interactions with microfluidic channel walls perturb the retention curves from the ideal predictions at large particle sizes. Further complications to field-flow fractionation including undesirable forces perpendicular to the flow direction, slip at channel walls and rectangular channel geometries are investigated. These theoretical studies lead to the proposal of several novel fractionation techniques, namely adverse-mode FFF, slip-mode FFF and polymer/depletant HC.

abstract: Biological fluids contain information-rich mixtures of biochemicals and particles such as cells, proteins, and viruses. Selective and sensitive analysis of these fluids can enable clinicians to accurately diagnose a wide range of pathologies. Fluid samples such as these present an intriguing challenge to researchers; they are packed with potentially vital information, but notoriously difficult to analyze. Rapid and inexpensive analysis of blood and other bodily fluids is a topic gaining substantial attention in both science and medicine. Current limitations to many analyses include long culture times, expensive reagents, and the need for specialized laboratory facilities and personnel. Improving these tests and overcoming their limitations would allow faster and more widespread testing for disease and pathogens, potentially providing a significant advantage for healthcare in many settings. Both gradient separation techniques and dielectrophoresis can solve some of the difficulties presented by complex biological samples, thanks to selective capture, isolation, and concentration of analytes. By merging dielectrophoresis with a gradient separation-based approach, gradient insulator dielectrophoresis (g-iDEP) promises benefits in the form of rapid and specific separation of extremely similar bioparticles. High-resolution capture can be achieved by exploiting variations in the characteristic physical properties of cells and other bioparticles. Novel implementation and application of the technique has demonstrated the isolation and concentration of blood cells from a complex biological sample, differentiation of bacterial strains within a single species, and separation of antibiotic-resistant and antibiotic-susceptible bacteria. Furthermore, this approach allows simultaneous concentration of analyte, facilitating detection and downstream analysis. A theoretical description of the resolving capabilities of g-iDEP was also developed. This theory explores the relationship between experimental parameters and resolution. Results indicate the possibility of differentiating particles with dielectrophoretic mobilities that differ by as little as one part in 100,000,000, or electrophoretic mobilities differing by as little as one part in 100,000. These results indicate the potential g-iDEP holds in terms of both separatory power and the possibility for diagnostic applications. / Dissertation/Thesis / Doctoral Dissertation Biochemistry 2015

abstract: Microfluidics has shown great potential in rapid isolation, sorting, and concentration of bioparticles upon its discovery. Over the past decades, significant improvements have been made in device fabrication techniques and microfluidic methodologies. As a result, considerable microfluidic-based isolation and concentration techniques have been developed, particularly for rapid pathogen detection. Among all microfluidic techniques, dielectrophoresis (DEP) is one of the most effective and efficient techniques to quickly isolate and separate polarizable particles under inhomogeneous electric field. To date, extensive studies have demonstrated that DEP devices are able to precisely manipulate cells ranging from over 10 μm (mammalian cells) down to about 1 μm (small bacteria). However, very limited DEP studies on manipulating submicron bioparticles, such as viruses, have been reported. In this dissertation, rapid capture and concentration of two different and representative types of virus particles (Sindbis virus and bacteriophage M13) with gradient insulator-based DEP (g-iDEP) has been demonstrated. Sindbis virus has a near-spherical shape with a diameter ~68 nm, while bacteriophage M13 has a filamentous shape with a length ~900 nm and a diameter ~6 nm. Under specific g-iDEP experimental conditions, the concentration of Sindbis virus can be increased two to six times within only a few seconds, using easily accessible voltages as low as 70 V. A similar phenomenon is also observed with bacteriophage M13. Meanwhile, their different DEP behavior predicts the potential of separating viruses with carefully designed microchannels and choices of experimental condition. DEP-based microfluidics also shows great potential in manipulating blood samples, specifically rapid separations of blood cells and proteins. To investigate the ability of g-iDEP device in blood sample manipulation, some proofs of principle work was accomplished including separating two cardiac disease-related proteins (myoglobin and heart-type fatty acid binding protein) and red blood cells (RBCs). Consistent separation was observed, showing retention of RBCs and passage of the two spiked protein biomarkers. The numerical concentration of RBCs was reduced (~70 percent after one minute) with the purified proteins available for detection or further processing. This study explores and extends the use of the device from differentiating similar particles to acting as a sample pretreatment step. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2017

The advent of microfluidic technology presents many difficulties but also many opportunities for separation science. Leveraging the potential of micro- and nanofluidic geometries is not only a matter of shrinking systems. Miniaturization can shift the relative importance of physical phenomena leading to separation. Theoretical and computational studies into the consequences of miniaturization are vital. Mesoscopic, multi-particle collision dynamics simulations are performed on polyelectrolytes and hard, colloidal solutes. Multiple variations of this simulation algorithm are implemented to achieve versatility for simulating non-equilibrium flows and dispersed solutes. The algorithm is extended to simulate the effects of finite Debye layers on the electro-hydrodynamics of electrophoresing macromolecules and used to study the electrophoresis of charged oligomers, polyelectrolytes and polyampholytes in both free-solution and confined geometries. Multi-particle collision dynamics simulations of hydrodynamic chromatography and field-flow fractionation are also performed to test the predictions of the derived unified, ideal retention theory. This unified, ideal retention predicts the transitions between multiple operational modes, including Faxén-mode FFF. Simulations and the theory show that increases in drag due to hydrodynamic interactions with microfluidic channel walls perturb the retention curves from the ideal predictions at large particle sizes. Further complications to field-flow fractionation including undesirable forces perpendicular to the flow direction, slip at channel walls and rectangular channel geometries are investigated. These theoretical studies lead to the proposal of several novel fractionation techniques, namely adverse-mode FFF, slip-mode FFF and polymer/depletant HC.