Date of Award

Winter 12-18-2019

Degree Type

Thesis

Degree Name

MS Chemistry

Department

Chemistry and Biochemistry

Advisor

Nicholas H. Snow, Ph.D.

Committee Member

Wyatt R. Murphy, Ph.D.

Committee Member

Yuri V. Kazakevich, Ph.D.

Keywords

Gas chromatography, capillary gas chromatography, carrier gases, nitrogen, helium

Abstract

Gas chromatography (GC) is one of the most widely used analytical techniques for the separation and analysis of volatile compounds. Solids, liquids, and gases, organic and inorganic materials, and large molecular weight compounds can all be analyzed via this technique. Gas chromatographic separations are fast, accurate, and reliable. One of the reasons why these separations are so efficient is because of the carrier gas. The purpose of the carrier gas is to carry the injected sample through the column. It is known as the mobile phase and does not interact chemically with the sample. Common carrier gases include helium, hydrogen, and nitrogen. Helium is the most frequently used, but increased demand has caused a worldwide helium shortage. This has forced scientists to look for alternative carrier gases and study how much they influence separation.

The purpose of this research is to explore the performance of nitrogen as an alternative GC carrier gas. Previous literature states that nitrogen is non-ideal because it yields long retention times due to the low optimum linear gas velocity and rapid band broadening. However, with nitrogen, it is also possible to generate the most efficient separations. Nitrogen is more cost-effective compared to helium. This research focuses on the comparison between nitrogen and helium carrier gases to determine whether nitrogen can be a replacement for helium. Compounds such as alkanes, essential oils, polycyclic aromatic hydrocarbons, and column test mixtures were all analyzed under temperature programmed conditions. Column performance calculations such as separation numbers, resolution, and efficiency were performed, and Van Deemter curves were created. Nitrogen proved effective and should be considered a reasonable alternative carrier gas in gas chromatography.

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