Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 151-154). Also available via the Internet.

Thesis (doctoral)--Lund University, 1994. / Added t.p. with thesis statement inserted.

Thesis (doctoral)--Lund University, 1994. / Added t.p. with thesis statement inserted.

Quantitation of the amount of finish applied during fiber manufacturing is an important industrial quality control process. Finish levels that are too low result in excessive fiber and mechanical wear. On the other hand, overly high finish levels may cause residue buildup on the processing equipment. Removal of the finish has traditionally been done with solvents such as chloroform or Freon followed by gravimetric or spectroscopic analysis of the removed material. Quantitation of low molecular weight oligomeric material is another important quality control practice for the fiber industry in that the presence of these species and their concentration affect the physical properties of the polymer. Also, excessively high concentrations of oligomers may result in residue deposits on processing equipment. Typical conventional methods for determining the concentration of oligomers present in fibers involve large quantities of organic solvent for removal of the oligomers followed by chromatographic analysis. Increased government regulation of chlorinated and other solvents has led to investigations of alternate methods of extraction. Several studies have shown that supercritical fluid extraction (SFE) using carbon dioxide as the extraction fluid is an important alternative to conventional organic solvent extraction for the removal of both textile finishes and oligomeric material. This research seeks to extend the previous studies regarding the application of SFE for the quantitation of finish and oligomers from nylon 6,6 fibers. The effects of pressure, extraction temperature, modifier percentage, static extraction time, and dynamic extraction time on the supercritical fluid extraction efficiency of nylon 6,6 oligomers were examined. Results from the SFE methods for both finish and oligomer extractions were compared to results from conventional solvent extraction. The extracted oligomers were identified by HPLC with coupled on-line atmospheric pressure chemical ionization mass spectrometry (APCI-MS) and HPLC fractionation coupled with off-line Liquid Secondary Ion Mass Spectrometry (LSIMS). / Master of Science

No description available.

The purpose of this research was to design a simple, novel interface for on-line coupling of Supercritical Fluid Extraction (SFE) with High Performance Reversed Phase Liquid Chromatography (HP-RPLC), and to explore its ability for quantitative analysis of analytes in different matrices. First, a simple interface was developed via a single one six-port injection valve to connect the SFE and LC systems. A water displacement method was utilized to eliminate decompressed CO2 gas in the solid phase SFE trap and connection tubes. To evalute this novel hyphenated system, spiked polynuclear aromatic hydrocarbons (PAHs) in a sand matrix were used as target analytes with the achievement of quantitative results. Also PAHs in naturally contaminated soil were successfully extracted and quantitatively determined by this hyphenated system. Compared to the EPA method (Soxhlet extraction followed by GC-MS), on-line SFE-LC gave precise (4-10% RSD) and accurate results in a much shorter time. Based on this hyphenated technique, a method for the extraction and analysis of hyperforin in St. John's Wort was developed under air/light free conditions. Hyperforin is a major active constituent in the antidepression herbal medicine-Hypericum Perforatum (St. John's Wort). Hyperforin is very sensitive to oxygen and light. There is no way to date to determine whether any degradation occurs during the sample-processing step in the analytical laboratory. On-line coupling of SFE-LC with UV absorbance/ electrospray ionization mass spectrometry (SFE-LC-UV/ESI-MS) provided an air/light free extraction-separation-detection system, which addressed this issue. Mass spectral data on the extract confirmed the presence of the major degradation compounds of hyperforin (i.e. furohyperforin and two of its analogues). Thus, the degradation process must have occurred during plant drying or storage. The feasibility of quantitative extraction and analysis of hyperforin by on-line SFE-LC was made possible by optimizing the extraction pressure, temperature, and modifier content. High SFE recovery (~90%) relative to liquid-solid extraction was achieved under optimized conditions. We then extended the interface's application to an aqueous sample by using a liquid-fluid extraction vessel. Quantitative extraction and transfer were achieved for the target analytes (progesterone, phenanthrene, and pyrene) spiked in water, as well as in real samples (urine and environmental water). During each extraction, no restrictor plugging was realized. Extraction temperature and pressure were optimized. Different amounts of salt were added to the aqueous matrix to enhance ionic strength and thus extraction efficiency. Methanol and 2-propanol were used as CO2 modifiers. Two modifier modes were compared, e.g. dynamically mixing modifier with the CO2 extraction fluid, and pre-spiking modifier in the extraction vessel. Surprisingly, we found pre-spiking the same amount of modifier in the vessel enhanced the recovery from ~70% to ~100% for progesterone, phenanthrene, and pyrene due to a "co-extraction effect". The last phase of our work explored the disadvantages/limitations of this hyphenated technique through the analysis of more highly polar phenolic compounds in grape seeds. Five types of SFE trapping adsorbent materials were evaluated in an effort to enhance the collection efficiency for the polar components. Pure supercritical CO2 was used first to remove the less polar oil in the seeds. Then methanol-modified CO2 was used to remove the polar components (e.g. phenolic compounds). Catechin and epicatechin (90%) were exhaustively extracted out of the de-oiled seed after 240 minutes with 40% methanol as modifier. Both singly linked (B-type) and doubly linked (A-type) procyanidins were identified by LC-ESI-MS, as well as their galloylated derivatives. Compared to the off-line SFE-LC approach, much less sample was required for extraction in the on-line method, since all the extracted components could be transferred to the LC column. Also, no extract processing/concentration step was needed in the on-line method. However, in the on-line mode, some polar compounds were lost (1) during the collection step (e.g. lower trapping efficiency on a single solid SFE trap when a high percentage modifier was used) and (2) during the water rinsing step (e.g. less retention of polar compounds on C18 trap). Therefore, this hyphenated technique is less desirable for the analysis of highly polar compounds. / Ph. D.

Supercritical fluids were introduced as mobile phases for chromatography and extractions in the early sixties. Over the past decade the technique has received increased attention, largely owing to the introduction of several commercial instruments and to the ease of adapting available commercial equipment for use in sfe and sfc. This dissertation examines the use of supercritical CO₂ as a mobile phase for chromatography and extraction. The first chapter explores the problems and provides background for the research. The physical properties of supercritical fluids are described and pertinent recent research is identified and summarized. The following chapter presents the design of three interrelated studies that investigate in-situ concentration, quantitative aspects of sfc, and quantitative aspects of sfe. The first of the three studies examined the exploitation of the innate properties of a supercritical fluid. Because the mechanism of elution with supercritical fluid mobile phases is based on solvation, it was possible in this study to concentrate analytes at the head of the supercritical zone. Concentration was followed by supercritical fluid chromatography. This allowed the analysis of sample components at part per billion levels. The use of supercritical fluids as mobile phases for chromatography and the quantitative nature of sfc with flame ionization detection was examined in the second study. Under numerous detector and injector configurations, a distinct decrease in response factors with an increase in carbon number was evident. Results showed that the decrease in response factors was related to an increase in CO₂ flow through the detector. The magnitude of the decrease was multivariably dependent. The third study dealt with the quantitative aspects of using a supercritical Oobile phase for the extraction of PNAs and pesticides from several matrices including contaminated soil. Results showed that sfe is a reliable, easy, and efficient (> 85% recovery) method of removing trace materials from contaminated soil. Implementation of a simple resistively heated collector was used to circumvent the problems of extracting damp matrices such as soil. The results and conclusions are presented in the final two chapters. / Ph. D.

Supercritical fluid extraction (SFE) continues to be explored as a feasible alternative to traditional Soxhlet and other types of extraction. In many cases SFE is cleaner, faster, and less expensive than the traditional types of extractions. This investigation has focused on the evaluation of Supercritical CO₂ extraction as a quantitative method for recovery of a hypolipidemic drug (tradename xenalipin) from an animal feed matrix. Initial emphasis of this study focused on the recovery of xenalipin from a the animal feed matrix employing a liquid solvent trap. By studying the effect of time of extraction versus recovery of drug, the liquid trap was shown to be inadequate. Further studies implemented the extraction of xenalipin from a filter paper matrix and the use of solid phase traps. This method of inquiry was use to evaluate the degree of recovery as related to the parameters of CO₂ density, extraction time, and flow rates of CO₂. After achieving quantitative extraction of xenalipin from filter these parameters were transferred to the animal feed matrix. The animal feed matrix was prepared using three different methods. Each matrix was evaluated for homogeneity of sample and ability to achieve quantitative extraction. / Master of Science

The extraction of fifteen (15) polymer additives with supercritical carbon dioxide which are used as antioxidants, uv stabilizers, process lubes, flame retardants and antistats from eight formulations of polystyrene is demonstrated and compared to traditional dissolution/precipitation extractions. The purpose of the study was twofold: 1) the development of a high performance liquid chromatography (HPLC) method(s) for the additives and 2) the determination of the viability of supercritical fluid extraction (SFE) for the additives from polystyrene. Separation of some of the additives was achieved using reversed phase liquid chromatography. Nine of the additives were assayed in this manner while, the remaining six additives could not be assayed using reversed phase liquid chromatography. In order to develop an extraction method for the additives, the effects of static extraction time, CO2 density, and temperature were first investigated. These preliminary extractions revealed that a static extraction period which afforded an opportunity for the polymer to swell combined with a high CO2 density and extraction temperature above the glass transition (Tg) yielded quantitative recoveries of the additives. Triplicate extractions of the various polystyrene formulations matched additive recoveries obtained by the traditional dissolution/precipitation method. / Master of Science