Chiral Excess: Measuring the Chirality of Geographically and Seasonally Different Geranium Oils

Abstract

Essential oils from Australian grown rose geranium (Pelargonium hybrid) G1 clone, were analyzed regularly over a three year period using chiral and normal column gas chromatography. The G1 oil was compared to other commercial geranium oils using ten key chiral compounds. Comparisons were made using the new concept called chiral excess (CE), the first eluting enantiomer minus the second eluting enantiomer, and total excess (TE), the sum of all the CE's. This concept allowed the chirality of geranium oils to be expressed as a single number. TE was used to help distinguish between 18 geographically different and 24 seasonally different commercial oils. Applications of TE include classification of other chiral-containing oils and the detection of adulterants in essential oils.

Key Word Index:

• Pelargonium hybrid
• Geraniaceae
• rose geranium
• essential oil composition
• enantiomeric distribution
• chiral excess
• total excess
• seasonal variation