Polyaniline as stationary phase for HPLC
This dissertation consists of two manuscripts. The first manuscript concerns the study of polyaniline as a stationary phase for high performance liquid chromatography and the elucidation of the mechanism for chemical separation in these chromatographic columns. The second manuscript is an analysis of the reproducibility and reliability of the experimental data. The objective is to prove that dispersion forces in polyaniline stationary phase are the dominant, non-Coulombic interactions that determine the order of the retention time of the analytes. In the first manuscript we compared the chromatograms of a pair of anionic analytes eluded in a polyaniline stationary phase and an ion exchange stationary phase. We concluded that the non-Coulombic part of the retention mechanism in polyaniline columns is dominated by an interaction that is not hydrophobic interaction and is significantly stronger than the non-Coulombic interaction in an ion exchange stationary phase. We next showed that the selectivities for the pair of analytes correlate with the tunable electronic polarizability of the polyaniline stationary phase. We used the pH value of the mobile phase to switch the polyaniline stationary phase to different electronic states with high or low electronic polarizabilities. We proposed that the dispersion interaction is the dominant non-Coulombic mechanism for retention. The relative importance of dispersion interaction in polyaniline stationary phase is due to its large polarizability from the delocalization of a large amount of polarons. We examined the relative strength of the Coulombic and the non-Coulombic interactions by changing the counter ion screening effect on the Coulombic part of the attractive force. We deduced that the dispersion force has as a strong influence on the selectivity as that of the electrostatic interaction. In the second manuscript we found the main systematic errors are due to overloading of analytes and higher concentration of buffer. After eliminating the two systematic errors we examined the uncertainties in measuring the void time and retention times. We collected the data and calculated the uncertainty of selectivity by propagation of the random errors in void time and retention times. We found that the estimated error in the selectivity is smaller than the measured.
"Polyaniline as stationary phase for HPLC"
Dissertations and Master's Theses (Campus Access).