Identification of Volatile Flavor Components by Headspace Analysis: A Quick and Easy Experiment for Introducing GC/MS

By placing a piece of chewing gum (Wrigley's) or a crushedpiece of hard candy (LifeSavers or Runts) into a vial, followedby GC/MS analysis of a five microliter sample of the headspace,students are able to identify several of the volatile flavoringcomponents which are present. The experiment has been usedsuccessfully with sophomore organic chemistry students, and withvisiting groups of talented high school students over a threeyear period. Identification is simplified by handing out a listof the structural formulas of some likely candidates. Some ofthe components that these students easily identity include ethylacetate, isobutyl acetate, isoamyl acetate, ethyl butyrate, benzaldehyde, benzyl alcohol, limonene, and cinnamaldehyde. Someof the more difficult to identify components include menthol,menthone, carvone, cineole, myrcene, alpha-pinene, beta-pinene,para-cymene, and gama-terpinene. Most of the major headspacecomponents give signals whose size is comparable to that of thecarbon dioxide which is present in each injection. Even withsplit injection, the background noise is trivial compared to thesignals from the major components. The experiments were carriedout with a commercially available tabletop GC/MS (Varian 3400with Saturn MS).