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  Home > JCE Print > Journal of Chemical Education > Issues > 2000  > October  >
In the Laboratory
Topics in Chemical Instrumentation
Determination of Aspartame and Caffeine in Carbonated Beverages Utilizing Electrospray Ionization-Mass Spectrometry
H. Robert Bergen III, Linda M. Benson, and Stephen Naylor
Biomedical Mass Spectrometry and Functional Proteomics Facility, Department of Biochemistry and Molecular Biology, Mayo Clinic Foundation, Rochester, MN 55905-0002
Cover
October 2000
Vol. 77 No. 10
p. 1325
Abstract
Mass spectrometry has undergone considerable changes in the past decade. The advent of "soft ionization" techniques such as electrospray ionization (ESI) affords the direct analysis of very polar molecules without need for the complex inefficient derivatization procedures often required in GC-MS. These ionization techniques make possible the direct mass spectral analysis of polar nonvolatile molecules such as DNA and proteins, which previously were difficult or impossible to analyze by MS. Compounds that readily take on a charge (acids and bases) lend themselves to ESI-MS analysis, whereas compounds that do not readily accept a charge (e.g. sugars) are often not seen or are seen only as inefficient adducts (e.g., M+Na+). To gain exposure to this state-of-the-art analytical procedure, high school students utilize ESI-MS in an analysis of aspartame and caffeine. They dilute a beverage sample and inject the diluted sample into the ESI-MS. The lab is procedurally simple and the results clearly demonstrate the potential and limitations of ESI-coupled mass spectrometry. Depending upon the instructional goals, the outlined procedures can be used to quantify the content of caffeine and aspartame in beverages or to understand the capabilities of electrospray ionization.
More Information
*  Citation
 Bergen, H. Robert, III; Benson, Linda M.; Naylor, Stephen. J. Chem. Educ. 2000 77 1325.
*  Keywords
 Analytical Chemistry; Instrumental Methods; Introductory / High School Chemistry; Laboratory Instruction; Mass Spectrometry
*  History
 Created:
Last Updated:		 September 22, 2000
April 15, 2005
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