Pinene Pinene exists in two forms, a-pinene (2,6,6,-Trimethylbicyclo[3.2.1.] hept-2-ene) and B-pinene (6,6,Dimethyl-2-methylenebicyclo[3.1.1.] heptane). Both forms are present in many essential oils but are mostly obtained from turpentine (obtained by the dry distillation of wood or other dry botanical material). Turpentine contains 58%-65% a-pinene and about 30% of B-pinene. Both pinenes are hydrocarbons and have a molecular weight of 136.23, and contain 88.16% of carbon, 11.84% of hydrogen. The a pinene obtained in North American oils is largely dextrorotary whereas the European oils are levorotary. The majority of B pinene, irrespective of its origin, is levorotary. As examples, a pinene and B pinene are found in Cedar Wood oil, orange oil, mandarin peel oil and in many fragrances. Like many essential oil constituents, the pinenes are thermally labile and need to separated by gas chromatography with considerable caution.

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Author: RPW Scott Book:Gas Chromatography
Section:GC   Applications   Food-and-Beverage-Products

dispersive interactions with the derivatized cyclodextrin. Courtesy of Supelco The columns were 30 m long, 0.25 mm I.D., carrying a film of stationary phase 0.25 mm thick of b-DEX™. The column was programmed from 40˚C to 220˚C at 4˚C/min. The helium flow velocity was 35 cm/s. Figure 48 Chromatogram of the Essential Oil From White Pine Leaves It should be noted that whereas the (–)-a-pinene is the first eluted enantiomer of a-pinene it is the (+)-camphene that is the first eluted of the camphene enantiomers. This tends to indicate that there is no rational procedure for predicting the order of elution of an enantiomeric pair

GC   Applications   Food-and-Beverage-Products

Author: RPW Scott Book:Gas Chromatography - Tandem Techniques
Section:GC-Tandem   Introduction

common use was disclosed.   Even the early examples given by James and Martin (2) in one of their first public lectures on the subject, included dramatic separations of multi-component mixtures that fired the imagination of chemists world-wide. For the first time the complex nature of these important materials could be displayed both quantitatively and qualitatively. An example of the separation of an essential oil using modern GC equipment is shown in figure 1 .     1. a-Pinene 7. gÐTerpinene 13. Geraniol 2. Camphene 8. Terpinolene 14. Neryl Acetate 3. b-Pinene 9. Linalool 15. Geranyl Acetate 4. Myrcene 10. Terpinene-4-ol 16. Caryophyllene 5. p-Cymene 11. a-Terpineol 17. trans-a-Bergamotene 6. Limonene 12. Neral 18. b-Bisabolen   Courtesy of Supelco, Inc.     Figure 7 A Chromatogram of Lime Oil

GC-Tandem   Introduction

Author: RPW Scott Book:Principles and Practice of Chromatography
Section:Principles   Applications   Gas-Chromatography   Essential-Oils

solutes, it is largely a dispersive stationary phase, and thus substances are eluted roughly in order of their boiling points (excepting very polar solutes). The introduction of the diphenyl groups contributes more to phase temperature stability than it does to solute selectivity. The column was 30 m long, 250 mm I.D. carrying a film 0.25 mm thick of stationary phase. Helium was used as the carrier gas at a linear velocity of 25 cm/sec(set at 155˚C). 1. a–Pinene 7. g–Terpinene 13. Geraniol 2. Camphene 8. Terpinolene 14. Neryl Acetate 3. b–Pinene 9. Linalool 15. Geranyl Acetate 4. Myrcene 10. Terpinene–4–ol 16. Caryophyllene 5. p–Cymene 11. a–Terpineol 17.trans–a–Bergamotene 6. Limonene 12. Neral 18. b–Bisabolen   Courtesy of

Principles   Applications   Gas-Chromatography   Essential-Oils

Author: RPW Scott Book:Gas Chromatography
Section:GC   Applications   Lime-Oil

a sample of lime oil is shown in figure 43. A SB–5 column, that contained poly(5%diphenyl-95%–dimethylsiloxane) as the stationary phase was used to carry out the separation. It is largely a dispersive stationary phase, although the diphenyl group will contribute some induced polarizability capability to interact with polar solutes. As a consequence substances are eluted roughly in order of their boiling points (excepting very polar solutes).   1. a–Pinene 7. g–Terpinene 13. Geraniol 2. Camphene 8. Terpinolene 14. Neryl Acetate 3. b–Pinene 9. Linalool 15. Geranyl Acetate 4. Myrcene 10. Terpinene–4–ol 16. Caryophyllene 5. p–Cymene 11. a–Terpineol 17. trans–a–Bergamotene 6. Limonene 12. Neral 18. b–Bisabolen   Courtesy of

GC   Applications   Lime-Oil

 
 
 

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