Project 4
Chem 361
Spring 2008
Gas Chromatography/Electron Impact Ionization-
Mass Spectrometry of Gasoline
In this project you will analyze two gasoline samples from the same pumping station by GC/EI-MS. One of the samples will have an octane rating of 87 and the other will have a rating of 92. This module will have the following learning goals.
1. Understanding of how temperature gradient GC works.
2. Understanding of electron impact mass spectrometry
3. Understanding fragmentation patterns in 70 eV electron ionization mass spectra
4. Gain an appreciation for the power of library searching in GC-MS
5. Gain an basic understanding of the process of petroleum refining
6. Gain a basic understanding of octane rating
Report:
· Obtain the spectra of each of the isomers of the C7 and C8 saturated alkanes in the data for the 92 rated gasoline. Identify them through library matching. Attempt to rationalize the fragmentation patterns with the branching patterns of the isomers.
· Compare the total ion chromatograms of the two samples and determine if there are obvious differences between the two samples. Investigate these differences and attempt to rationalize the results based on the octane rating scale.
· Characterize the gasoline samples in terms of the molecular weight range of most of the hydrocarbons in these samples.
· Discuss the octane rating and the oil refining process and attempt to relate these topics to your experimental results.