Investigation of selective binding interactions for analytical separation and determination of pharmaceuticals and toxins

The technique of molecular imprinting was employed to produce a polymer material that was utilized as a chromatographic stationary phase and solid phase adsorbent for the improved separation of the asthmatic drug theophylline and interferents from human serum samples. The molecular imprinting technique was based on creating cavities, in a highly cross-linked polymer matrix, which corresponded to the size and shape of the print molecule. Removal of theophylline print molecule by solvent extraction left behind monomer functional groups at defined positions in a spatial arrangement that was complementary to the structure of theophylline. The MIP material possessed an inherent selectivity for the print molecule and was resistant to mechanical stress, heat, acids, bases, water and organic solvents.; The ground polymer particles were packed into a column. Solvents with ranging chemical properties such as polarity and protic nature eluted theophylline through the MIP column and the degree of theophylline retention was determined. These studies elucidated the molecular recognition process that provided the selective binding of theophylline. More specifically, the roles of intermolecular interactions such as hydrogen bonding and electrostatic forces between the theophylline molecule in a sample solution and the functional groups of the MIP cavities were implicated in the molecular recognition process.; The molecular recognition of theophylline by the MIP column was optimized in the presence of non-polar and aprotic solvents, which were unable to interfere with the hydrogen bonding and electrostatic interactions. This resulted in the complete retention of theophylline while interfering compounds were flushed through the column by the solvents. The bound theophylline could rapidly be desorbed from the column with a very small volume (20 muL) of a polar and protic solvent for quantification by UV detection. The developed approach was labeled molecularly imprinted solid phase extraction - pulsed elution. (MISPE-PE). The MISPE-PE technique also allowed for analyte enrichment or preconcentration through injection of a relatively large volume of dilute sample solution, thus improving the detection limit of theophylline.; Multiple sample additions and large-volume sample circulation can be used with the high-affinity antibodies to achieve lower detection limits. (Abstract shortened by UMI.)...