Capillary electrophoretic and mass spectrometric analysis of some pharmaceutical and agrochemical compounds

• Main Author: Severs, J. C.
• Published: Swansea University 1995
• Subjects: 543
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638796

The relatively new separation technique of capillary electrophoresis, with its ability to provide rapid, high resolution separations based on electrophoretic mobility differences, has developed enormously over the last decade. Although the technique was first interfaced to mass spectrometry within a few years of its conception, when the studies described here were undertaken there were few reports of the use of such combined systems. The objectives of these studies were to conduct further investigations into the interfacing of capillary electrophoresis with mass spectrometry via atmospheric-pressure ionisation sources. The system was then to be used for the analysis of some polar and ionic compounds of interest to the pharmaceutical and agrochemical industries. The fundamentals of capillary electrophoresis, mass spectrometry and combined systems are reviewed. Interfaces developed in these studies for capillary electrophoresis-mass spectrometry for a range of capillary electrophoresis instruments and atmospheric-pressure ionisation sources are described and detailed practical instructions for their use are given. The results obtained for the separation and detection of analytes in three sets of compounds; some herbicide analogues, some <I>β</I>-blocker drugs and some small peptides are presented in Chapter 3. Transient capillary isotachophoresis methods have been developed and optimised for all three sets of analytes, improving concentration detection limits by at least an order of magnitude. The use of small-diameter capillaries has also been shown to improve sensitivity. Separation of two structurally similar herbicide analogues has been effected by the addition of an optimised concentration of a cyclodextrin to the electrophoresis buffer, and use of cyclodextrins in capillary electrophoresis-electrospray ionisation systems has been studied. Use of deuterated buffers in the combined system has been shown to improve certain separations and, through mass spectra showing deuterium exchange, provide further structural information for analysis. Practical considerations for successful completion of such studies are described.