Hyphenated fourier transform infrared spectrometry :techniques for separations and analysis
Jordan, Sheri Lynne
MetadataShow full item record
The following work describes the instrumentation and application of hyphenated FT-IR techniques specifically involving supercritical fluid extraction (SFE), supercritical fluid chromatography (SFC), and liquid chromatography (LC). Three studies are presented. The first involves the application of SFE/FT-IR towards the extraction of finishes from textile fibers. SFE has previously been applied to less complex finish systems. The proposed method making use of intermediate trapping is viable for more complex systems that show limited solubility in a supercritical fluid. Quantification of the percent finish on yarn was performed and results were favorable when compared with plant data. The range of applications was expanded to on-line SFE/SFC in the extraction and analysis of components from the polymer matrix itself. SFE/SFC/FT-IR was used to identify extractable components from a variety of Nylons. Following identification of one of the primary extractables, caprolactam, SFE/SFC was used to quantitate the amount of residual starting material in a Nylon copolymer. The second study involves the extractables in polystyrene which is a softer polymer with respect to solubility of components in supercritical CO 2. Dimers and trimers as well as processing agents were identified via FT-IR with relatively mild supercritical extraction conditions. Following these two studies was the expansion of hyphenated FT -IR to mobile phase elimination. A system optimization was carried out using polymer additive standards. The effects of nebulizer flow, sheath flow, and sheath temperature were shown. The data were analyzed at in terms of library matches as well as GramSchmidt reconstruction peak heights. Peak intensities were the primary source for choosing optimum conditions. Under optimized conditions, approximately 200 ng of analyte were analyzed and found to be above the limit of detection. The applicability of the interface was demonstrated by the identification/analysis of triclosan, an antibacterial agent, in Colgate toothpaste. Aside from the identification of the analyte this study was used to show the effect of deposition parameters such as disk rotation rate as well as the effectiveness of FT-IR spectral library searches. The analysis of triglycerides was also carried out to show the effectiveness of using LC/FTIR for viscous liquids which are difficult analytes to deposit onto a solid substrate. Using this FT-IR technique allowed one to look at the degree of saturation/unsaturation in an olive oil sample. The linearity of the method was shown using a set of triglyceride standards. Lastly, the feasibility of using the commercially manufactured mobile phase elimination interface for SFC was demonstrated. Additive standard was deposited using both pure and methanol modified CO2. No effluent split mechanism was used for decompressed flows up to 150 mL/min. Detection limits are proposed to fall in the low (10 - 25) ng range. The infrared spectra are enhanced over those acquired with a flow cell interface because CO2 absorbance bands no longer obscure a portion of the analyte absorption spectrum.
- Doctoral Dissertations