Recent advances in the use of supercritical fluids in analytical chemistry.

摘要

Supercritical fluids are important in all aspects of analytical chemistry and discussed in the dissertation is the development of analytical processes that utilize supercritical fluids.;The study of coal desulfurization with supercritical ethanol was investigated. Untreated and pyrite removed samples were investigated. It was found that between 64% and 79% of the total sulfur could be removed with the combined pyrite removal/extraction process. It was also found that the reactions that cause liquefaction were also causing desulfurization. Thermolytic bond cleavage, hydride donation, and alkylation were the predominant reactions that were occurring between the ethanol and the coal matrix.;Supercritical fluid chromatography with novel stationary phases was also investigated. Interaction of solutes with porous glassy carbon was studied to try to determine the retention mechanism for this material in SFC. Previous studies did not take into account the separation of positional and geometrical isomers. These separations are easily achieved when using PGC. The molecule set was chosen because of they were similar except for three dimensional shapes. In this study it was found that the planarity of the solute, monitored by the ;A novel treated PGC was also investigated. When triethylamine is dissolved in supercritical carbon dioxide and flushed through a PGC column, a strong interaction takes place. It is beneficial because the selectivity of the column is maintained but decreased retention is observed for all types of solutes. The interaction is strong, the decrease in retention remained stable for the entire testing period, in excess of 14 days.;Finally, a novel interface to link supercritical fluid chromatography to a mass spectrometer was developed. The expansion of a supercritical fluid into the vacuum chamber causes clusters to form. These clusters are ionized in a field ionization type process. The ability to control the extent of fragmentation is a major advantage of this technique. Varying the cluster size, by changing the density of the fluid, makes it possible to control the extent of fragmentation.