Development and applications of electrically-driven separation methods.

The use of non-aqueous media in CE was investigated primarily in an attempt to identify alternative mobile phases for application in CEC. Several solvents were found to support a rapid EOF even without the presence of a supporting electrolyte. These initial experiments led to the development of a separation involving an active pharmaceutical ingredient (Cimetidine) and a series of related materials. The latter displayed alternative selectivity relative to a comparable aqueous-based separation and offered a number of advantages. However, the underlying fundamental principles that govern separations in non-aqueous media were not well understood and method development was somewhat of a "black art". Further studies were therefore undertaken in order to gain an understanding of the mechanisms that influence separations in non-aqueous media. Under certain conditions the mode of separation appeared to be based on some form of interaction with the background electrolyte and the choice of a suitable EOF marker was not straightforward. HPLC separations of EPA priority pollutant phthalate esters were developed to assess the ease by which they could be transferred to CEC and determine any advantages offered by the electrically-driven technique. The practicalities of fabricating columns for CEC separations are critically discussed along with the unsuitability of some of the stationary phases employed. Attempts to utilise non-aqueous media in CEC separations are also described. A series of "real" applications were undertaken to assess the practicality of various electrically-driven separation techniques. The latter comprised a series of alkyltin compounds, the pesticide pirimicarb and its related metabolites and the determination of ethylenediammine (EDA). No meaningful separations were achieved with alkyltin compounds. However, the use of NMF as a non-aqueous mobile phase for CEC was demonstrated. Investigations involving EDA also did not lead to a successful separation. However, issues with the proposed derivatisation schemes were uncovered. The separations involving pirimicarb clearly demonstrated the enhanced scope available for method development offered by the various modes of CE that are available. Only partial separations were possible using CE in both aqueous and non-aqueous media. However, complete resolution of the 4 structurally similar materials was achieved using MEKC.