Zhaohui Luo

Date of Award

8-2006

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

Advisor

Touradj Solouki

Second Committee Member

Howard H. Patterson

Third Committee Member

Carl P. Tripp

Abstract

There were two goals in this dissertation: (I) Employ gas chromatography coupled with Fourier transform ion cyclotron resonance mass spectrometry (GCIFT-ICR MS) as an analytical tool to characterize complex unknown samples, such as crudelrefined petroleum products and disinfection by-products (DBPs) in drinking water. (2) Measure the gas-phase basicity (GB) of the GC eluting analytes in real time. Chapter 1 includes a brief introduction on the developing history of the GCIFTICR MS and overviews of the multidimensional GC/FT-ICR MS and online measurement of GB by GCIFT-ICR MS. Chapter 2 contains details on using GCIFT-ICR MS to analyze DBPs. The occurrence of waterborne infectious diseases has been greatly reduced since water disinfectants (e.g., chloramine, chlorine-dioxide, chlorine and ozone) were used to clean drinking water. However, hundreds of harmful disinfection by-products (DBPs) have been identified since 1974. We show the advantage of using GCIFT ICR MS for DBP identification; high mass resolving power (e.g., m/Δ50%≈13,500) and ultrahigh MMA (e.g., average error <5 ppm) allow DBP identification at the highest level of confidence. In Chapter 3, we show that multidimensional GCIFT- ICR MS provides proton affinity (PA) values as an additional analysis dimension. When complex sample mixtures such as crude petroleum that contain several isomers (e.g., isomers of C8Hl0) are analyzed, many of the isomers tend to elute from the GC column at a very close retention time. Often mass spectral patterns of these isomers are also similar and hence sample characterization becomes challenging. As a consequence, conventional GCIMS may not be able to distinguish various isomers from each other. Real time PA "bracketing" results of the GC eluting analytes in our 7-tesla GC/FT-ICR MS provide an additional dimension to conventional GCIMS analysis. In addition, we show that the average mass measurement error was less than 3 ppm and various isomers of C8H10 were identified individually. In Chapter 4, utilizing the 7-tesla GC/FT-ICR MS in our lab, we developed a new method to determine the GB data of neutral samples in real time. Methods such as "equilibrium" and "bracketing" are the classic ways of determining GB and PA. Compared with the traditional methods, fewer experiments are required. As a consequence, time and cost are saved. We demonstrate that, using GCET-ICR MS, thermodynamical data with relative accuracy of better than ± 0.5 kcal.mol-1 can be acquired.

Download

Share