Gas Chromatography Applications
Gasoline
The most common hydrocarbon analysis carried out by GC is probably that of gasoline. The analysis of gasoline is typical of the type of sample for which GC is the ideal technique. It is this type of multicomponent mixtures containing very similar compounds that need the high efficiencies available from GC for a successful analysis. The separation of a sample of gasoline carried out on a long open tubular column is shown in figure 35. It is clear that the column had a very high efficiency which was claimed to be in excess of 400,000 theoretical plates. The column was 100 m long and only 250 mm I.D., carrying a film of the stationary phase, Petrocol DH, 0.5 mm thick. Petrocol DH is specially designed stationary phase for the separation of hydrocarbons and consists of bonded dimethylsiloxane, a very dispersive type of stationary phase, retaining the solutes approximately in the order of their increasing boiling points.
| 1. Isobutane | 12. 3–Methylhexane | 23. o–Xylene |
| 2. n–Butane | 13. 2,3,4–Trimethylpentane | 24. 1–Methyl–3–ethylbenzene |
| 3. Isopentane | 14. n–Heptane | 25. 1,3,6–Trimethylbenzene |
| 4. n–Pentane | 15. 2,5–Dimethylhexane | 26. 1,2,4–trimethylbenzene |
| 5. 2,3–Dimethylbutane | 16. 2,4–Dimethylhexane | 27. 1,2,3–Trimethylbenzene |
| 6. 2–Methylpentane | 17. 2,3,4–Trimethylpentane | 28 Naphthalene |
| 7. 3–Methylpentane | 18. Toluene | 29. 2–Methylnaphthalene |
| 8. n–Hexane | 19. 2,3–Dimethylhexane | 30. 1–Methylnaphthalene |
| 9. 2,4–Dimethylpentane | 20. Ethylbenzene | 31. Dimethylnaphthalene |
| 10. Benzene | 21. m–Xylene | |
| 11. 2–Methylhexane | 22. p–Xylene |
Courtesy of Supelco Inc.
Figure 35 The Separation of Gasoline
