Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: solution 13C-NMR study; olid phase peptide synthesis; bicyclic peptides; ammonium ionophores; valinomycin; ion selective electrode. Includes bibliographical references (p. 63-65).

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 1977 / Includes bibliographical references. / Ph. D. / Ph. D. Massachusetts Institute of Technology, Department of Chemistry

Thesis (Ph.D.(Chemistry))--University of Pretoria, 2004. / Summaries in English and Afrikaans. Includes bibliographical references (leaves 229-238). Also available online.

Thesis (PhD)--University of South Australia, 1996

Thesis (Ph.D.)--Tufts University, 2005. / Adviser: Samuel P. Kounaves. Submitted to the Dept. of Chemistry. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (Ph.D.)--Case Western Reserve University, 2009 / Department of Biomedical Engineering Abstract Title from OhioLINK abstract screen (viewed on 10 April 2009) Available online via the OhioLINK ETD Center

Three areas related to Polymer Membrane Ion-Selective Electrodes were investigated. The first two concered (1) their application to analysis of organic cations and pharmaceuticals, and (2) the use of electrochemically polymerized films for potentiometric sensors. The third area focused on the development of a computer controlled data acquisition system for studying Ion Transport at the Interface of Two Immiscible Electrolyte Solutions (ITTIES). Coated wire Polymer Membrane Ion-Selective Electrodes (PMISEs) based on dinonylnapthalenesulfonic acid (DNNS) were prepared for several alkylammonium ions and pharmaceuticals. Selectivity coefficients and other operational characteristics were predictable from calculated distribution constants. Specifically, Log k ᵖᵒᵗ(i)(j) values increased linearly with carbon number in a homologous series of alkylammonium ions. Among cations of the same carbon number, interference increased tenfold with each additional substitution in going from quaternary, tertiary, secondary and primary alkylammonium ions. Addition of hydrophilic subtituent groups to cyclohexylammonium interferents further diminished electrode response. Electrodes for several important pharmaceuticals, namely cocaine, methamphetamine, methadone, protriptyline, cimetidine, lidoflazine, verapamil, acebutalol, diltiazem, and nicardipine, displayed nearly theoretical response down to micromolar concentrations. Their selectivity was consistent with calculated distribution constants. Selectivity was independent of sensitivity, suggesting that the magnitude of each was determined by the distribution of both the free cation and the association complex of this cation with DNNS. The polymerization of phenol derivatives onto copper rendered the resulting films responsive to counter-ions of the electroactive species present in the polymerization medium. Those incorporating Aliquat 336 (tricaprylmethylammonium chloride) showed response to various anions, while others prepared using a sulfonated phenol derivative (m-hydroxybenzenesulfonic acid) responded to tributylammonium. The films had short lifetimes due to poor adhesion to the copper substrate. Construction of a computer controlled data acquisition system provided a rapid method for obtaining electrocapillary data simultaneously with the current-scan polarogram. The system was evaluated by observation of ion-transfer of a variety of alkylammonium ions.

The lifetime of the polymer membrane ion-selective electrode is, in general, short when compared to that of the glass pH electrode. It is the manner in which the elctroactive materials are entrapped in the ion-selective membranes which accounts for this lifetime difference. In the polymer membrane electrode a high molecular weight electroactive material is dissolved in the plasticized polymer membrane. Because it is hydrophobic, this material is much more compatible with the low dielectric membrane phase than with the aqueous analyte phase. It, of course, has some solubility in the aqueous phase and, in time, leaches from the membrane. In the glass pH electrode, the electroactive material is the SiOH group which is covalently attached to the insoluble glass membrane. Because it is attached, it cannot be leached from the membrane. The purpose of this study was to investigate the possibility of covalently attaching the electroactive material to the polymer membrane in polymer membrane electrodes. In this weay, it was hoped that electrodes with much longer lifetimes could be obtained. Cation selective electrodes based on sulfonated polystyrene were investigated first. Sulfonation was accomplished by dipping polystyrene membranes into chlorosulfonic acid. Electrodes of both the conventional (i.e., with internal reference) and coated-wire types were prepared. Neither gave satisfactory response. Cation selective electrodes based on the perfluorinated, sulfonic acid containing ion exchange polymer NAFION 120® were investigated next. This material produced well-behaved Cs⁺ electrodes but electrodes responsive to larger cations (e.g., tetrapropylammonium and dodecyltri-methylammonium) could not be obtained. This may be due to ion-pairing in the membrane phase between these larger cations and the polymer bound sulfonate groups. To help answer some of the questions encountered during these investigations of electrodes based on covalently attached sulfonate groups, polymer membrane electrodes based on dinonylnaphthalenesulfonic acid were prepared and investigated. These electrodes were found to have very great selectivity for high molecular weight organic cations relative to inorganic and smaller organic cations. This type of selectivity is analogous to that obtained in ion pair solvent extraction of cations with a high molecular weight anionic species. Since a number of species of clinical, biological and toxicological interest are, at physiological pH, high molecular weight organic cations, electrodes based on dinonylnaphthalenesulfonic acid show great promise for determination of such species. An electrode for the determination of the drug phencyclidine was prepared to demonstrate the potentialities of drug analysis with this type of electrode. A microcomputer-based potentiometric analysis system was used to collect and analyze the data in this study. This system was one of the first stand-alone microcomputer systems employing a high level computer language to be described. The IMSAI 8080 Microcomputer and the computer language CONVERS were used.

Fluoride ion is an accompanying impurity in a wide variety of chemical gypsum throughout the world. In this study, the Ion Selective Electrode (ISE) method, the Ion Chromatography (IC) method and the standard Willard and Winter method of fluoride analysis were adapted and compared for use in the quantification of fluoride in South African chemical gypsum. During the use of ISE, the pH of sample solutions was found to be a critical parameter for the results to be meaningful. An operating pH of approximately 5 was suitable for consistency of results. It was important to ensure the existence of the ionised form of fluorine in solution, because the detection was based on the sensitivity of the membrane electrode to this species. In the case of the Willard and Winter method, the traditional visual indicator titration was replaced by a more sensitive spectrophotometric detection, because of low fluoride levels in the chemical gypsum. The parameter sensitive reaction rate approach was adapted, and the reaction allowed to go to completion to enable measurement with a bench top spectrophotometer. The IC method required a good separator since fluoride ions usually eluted too early for detection on common ion exchange columns. The data handling of the chromatographic software was thoroughly examined and consistent integration of the chromatograms maintained. Sample preparation of the chemical gypsum involved particle size reduction through grinding. No trend between fluoride impurity and the particle size of the sample was observed. <p. The quantity of fluoride in Kynoch and Omnia phosphogypsum were found to be 0.10% and 0.04% respectively. The Tioxide chemical gypsum, titangypsum, was found to contain in the region of 0.02% fluoride. Generally, the level of fluorine (F) has to be reduced to about 0.2% before phosphogypsum can be used as substitute for natural gypsum in the cement industry. The aim of this study is to critically evaluate three analytical methods, namely, the Willard and Winter standard method of fluoride analysis, the ISE method, and IC as applied in the quantification of fluoride in chemical gypsum. Secondly, the efficiency of treatment of the chemical gypsum with water, lime and sulphuric acid was investigated. The ISE method was found to be faster and relatively simpler versus both Willard and Winter and the IC methods. The IC method was quite superior for indicating general complexity of the sample and it was faster than the Willard and Winter method. The standard Willard and Winter method was generally found to be long and tedious. The three methods validated one another as percentages of fluoride in the chemical gypsum samples were the same. The study indicated that a sulphuric acid pretreatment of the chemical gypsum was the most effective (90%) in the removal of fluoride impurity compared to the lime treatment and water washing (9%). However, the water washing would be inexpensive for practical treatment of chemical gypsum at plant level. / Thesis (PhD(Chemistry))--University of Pretoria, 2006. / Chemistry / unrestricted

Thesis (M.S.)--Mississippi State University. Department of Chemistry. / Title from title screen. Includes bibliographical references.