Interpreting Gas Chromatographs and using data to select aromatherapy grade / therapeutic grade essential oils - an article by Joie Power, Ph.D

Chromatographs (gas chromatography) show the relative amounts of the various organic components that make up essential oils. The primary types of components include:

Component	Therapeutic Action	Toxicity / Skin Irritation
Alcohols	Antiseptic, antiviral, bactericidal	Low
Aldehydes	Antifungal, anti-inflammatory, disinfectant, sedative	Moderate
Esters	Antifungal, antimicrobial, sedative, antispasmodic	Low
Ketones	Anticatarrhal, cell proliferate, expectorant, vulnerary	High
Lactones	Anti-inflammatory, antiphlogistic, expectorant, febrefuge	Moderate to High
Oxides	Expectorant	Moderate
Phenols	Antiseptic, bactericidal, disinfectant, stimulant	Moderate to High
Terpenes	Anti-inflammatory, antiseptic, antiviral, antibacterial, (some are analgesic or stimulant)	Generally Low

In simple terms, when choosing an essential oil, one wants high therapeutic value and low toxicity. There are many different compounds within each of the major categories - altogether there are several hundred individual chemical substances that are found in essential oils. This makes it difficult to evaluate oils chemically. Even though a chromatograph may show only a few of the constituents of an oil, one still needs knowledge of many individual substances and their properties to read a chromatograph.

However, an illustration will show some of the basics:
Below are two chromatographs (with reports) - one is for Lavender Provence and one is for Lavender Dalmatian. I prefer the Lavender Provence (which is what we sell). Here is why:
A "good" Lavender contains a high proportion of esters and alcohols and a low proportion of camphor. The esters are especially prized in Lavender. "The constituents of different species differ in their content of the ester, linalyl acetate due to altitude. If lavender is grown above 2,000 feet, the ester content is increased, producing a more valuable oil." - quoted from the textbook for Aromatherapy Certification of the Australasian College of Herbal Studies.

Both the Provence and Dalmatian Lavenders are high in Linalool - a terpenoid alcohol that is low in toxicity and has good antiviral and antibacterial properties. Both are also low in camphor, which is a ketone and therefore a strong irritant. However even a quick glance at the charts shows that the Lavender from Provence is MUCH higher in Linalyl Acetate, an ester which is very low in toxicity and is highly valued for it's therapeutic effects. It is Linalyl Acetate which gives Lavender its' famous calming properties. Therefore, while either of these lavenders will have good antiviral and antibacterial properties, the Lavender Provence has outstanding calming and antispasmodic properties whereas the Lavender Dalmatian will have a less calming effect.

The Lavender Provence used by SomaTherapy Essential Oils costs our company, Dreaming Earth Botanicals, considerably more than the Lavender Dalmatian but we feel that the very superior quality of the Lavender Provence is worth the extra cost even though our profits might well be higher if we sold the cheaper oil.

Lavender Provence (organic)

GC-MS Analysis Report

Peak Area	Peak Time	Peak Scan	Marker Text
1.064	0:16:06	357	Pinene or Beta-Myrcene
7.432	0:17:04	414	Ecalyptol; 1:8 Cineole
31.909	0:18:07	475	Linalool
7.518	0:19:07	534	Camphor
3.282	0:19:35	561	Borneol
5.317	0:19:43	569	CAS 562-74-3
27.504	0:20:46	630	Linalyl Acetate
3.585	0:21:14	657	Geraniol Acetate
1.362	0:23:58	817	Farnesene
1.085	0:24:01	820	Caryophylene

Instrument: VG70E
Notes: MS/LB CB5 50m 1.2u 40(5)>250@10 10m/m spli 10psi inj 220 - 1.2x10-6 - 10mg in 1ml DCM 1ul inj

Lavender Dalmation

GC-MS Analysis Report

Peak Area	Peak Time	Peak Scan	Marker Text
0.571	0:15:57	578	a-Pinene
3.404	0:17:40	678	Ocimene Isomer
0.732	0:17:50	688	d-Limonene
7.369	0:17:54	692	Eucalyptol
40.241	0:18:52	748	Linalool
1.952	0:20:03	817	Camphor
1.453	0:20:21	834	Hexyl Butanoate
7.234	0:20:32	845	endo-Borneol
7.084	0:20:38	850	Terpinen-4-ol
6.281	0:21:31	902	Linalyl Acetate
0.850	0:22:00	930	Lavandulyl Acetate
2.713	0:24:47	1091	b-Farnesene

Instrument: VG70E
Notes: MS/LB CB5 50m 1.2u 40(4)>250@10 30m/m spli 15psi inj 250 - 1.2x10-6 16.3mg