| Nano-ESI interface is an efficient ion source, however, it is susceptible to clogging. Our research group developed a porous polymer monolith assisted electrospray emitter. Our in-house developed interface filters out debris and prevents capillary clogging. Furthermore, the PPM assisted interface has enhanced sensitivity compared to a commercial nanospray emitter over a range of flow rates and solvent compositions tested. Yet, the PPM assisted electrospray interface is not stable when used to spray highly aqueous solution (aqueous content > 70%). Highly aqueous solutions tend to spread to the hydrophilic fused silica surface at the exit aperture causing signal instability. The PPM-filled capillary sprayer has been re-designed to completely eliminate the fused silica surface at the exit aperture. The new design, named the external PPM sprayer, generates an electrospray directly from a PPM externally attached to the capillary. When comparing the signal stability of an external PPM sprayer, a PPM-filled capillary sprayer and a commercial nanospray emitter, the external PPM sprayer's stability approaches that of the commercial nanospray emitter and is superior to the PPM-filled capillary sprayer.; The thesis also investigates the applicability of PPM as a reverse phase chromatographic medium. The effect of the chemical nature and physical structure of methacrylate PPMs on the separation performance was studied. C18, C12, C8 and C4 methacrylate PPM columns were used to study the influence of chemical properties on separation efficiency whereas various densities of C4 PPM columns were used to study the effect of the physical structure of the PPM on separation efficiency. C18 methacrylate PPM is found to be best for retaining small molecules, C12 and C8 PPM are best for retaining the intermediate sized molecules, and C4 PPM is best for retaining large molecules. Increasing the density of the PPM also improves PPM's retention properties, however, the separation efficiency is low due to poor analytes mass transfer in the dense PPM. When using PPMs both as an ESI interface and as separation media in nanoLC-MS application, the number of physical connections (dead volume) was reduced, improving peak resolution. |
