EFFECTS OF PRESSURE ON ION EXCHANGE AND ION PAIRING CHROMATOGRAPHY.
Abstract
In this thesis, the effects of pressure on retention in cation exchange and in reverse phase liquid chromotography are presented. In the first section of this thesis, the effects of pressure up to 345 MPa (50,000 psi) on a reverse phase ion pairing system were studied in 50% methanol-water. Retention increased by a factor of 3.2 for methyl orange when the pressure was increased to 241 M.Pa (30,000 psi) and still larger (not measurable) at 345 m>a (50,000 psi). The retention of methyl red was increased by a factor of 2.2 by pressure of 241 MPa (30,000 psi) and by a factor of 2.5 by 345 MPa (50,000 psi). When the methanol concentration was increased to 75%, retention increased by a factor of 2.6 between 68.9 MPa (10,000 psi) and 345 MPa (50,000 psi). Other variables studied were concentration of counter ion, pH and temperature. For methyl orange, retention decreased with pH, whereas for methyl red, it increased. The effect of tetrahexylammonium ion concentration on retention was linear in the working range 0.5 mM to 2.0 mM. ill samples eluted faster with increased temperature. In the second part of the thesis, the effects of pressures up to 360 MPa (52,000 psi) on the capacity factors of sodium, potassium, rubidium, lithium, and magnesium ions were studied using nitrate eluents. The capacity factors, corrected for compression, were changed by almost 25% for rub1d1um and potassium ions by going from atmospheric pressure to 360 MPa. The corrected capacity factor for magnesium ion changed 15%, whereas those for lithium and sodium were essentially unchanged. The effect was attributed to changes in sizes of the hydrated cations.
Degree
Ph.D.
Subject Area
Analytical chemistry
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.