Some novel approaches to chromatographic and electrophoretic separations in biopharmaceutical analysis
Walshe, Michaela (1996) Some novel approaches to chromatographic and electrophoretic separations in biopharmaceutical analysis. PhD thesis, Dublin City University.
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Recent developments in the field of stationary phases for liquid chromatography and their use as solid-phase extraction(SPE) materials are discussed in chapter 1. In chapter 2, the use of a mixed-mode stationary phase (C18/SCX) for HPLC and its retention properties was then examined by variation of a number of parameters, including pH, ionic strength and buffer cation. A comparison was also carried out using a conventional Cl 8 column.
The use of this mixed-mode column was further investigated in chapter 3 for the simultaneous determination of propranolol and furosemide in human plasma. Development of the chromatography and the extraction procedures from first principles are also described. Two sample clean-up procedures were examined: liquid/liquid extraction and column switching. Each of these methods was validated and a comparison of the methods was carried out.
Chapter 4 then describes how “molecular imprinting” was used to create a chiral environment which would allow the separation of one enantiomer from the other, and which might find application in the area of solid-phase extraction and capillary zone electrophoresis. This work was based on the monomer most commonly used in molecular imprinting, i.e. methacrylic acid. It was then decided to modify this monomer and incorporate a chiral group, and use this monomer for polymerization against the target molecule propranolol. Polymers were also prepared using methacrylic acid to 7- hydroxy-coumarin (7-OHC) under a number of conditions.
In chapter 5, the polymer prepared to 7-OHC was packed into cartridges and applied to the determination of 7-OHC in urine by capillary zone electrophoresis (CZE). The polymer prepared to S-propranolol was also used as an additive in the buffer to enhance the CZE separation between the R- and S- enantiomers of the parent drug.
The thesis concludes with a critical appraisal of the work carried out in the thesis and suggestions for future research.
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