Separation of essential oils by liquid chromatography

Journal of Clrronratograplry, 114 (1975) 258-260 0 Elsevicr Scientific Publishing Company, Amsterdam CHROM.

-

Printed

in The Netherlands

8403

Note Separation

of essential

oils by liquid

chromatography

HISASHI KOMAE and NANAO HAYASHI Faculty of h?egratcd Arts artd Scictrces, Hiroslritw Uttivcrsity, Hirosiritm 730 (Japm) (Rcccived March IOth, 1975)

Essential oils consist. of mixtures of volatile compounds tllat are often complex, and almost any type of organic compound may be found. In genera!, the analysis of essential oils is performed by means of gas chromatography, as tlley contain volatile compounds. Liquid chrotiatograpky. however, is tile preferred metllod for evaluating such materials, as they may be sensitive to changes in temperature. Gel permeation chromatography (GPC) is a technique used for the separation of polymeric materials on tile basis of molecular size. The use of ,uStyrage! column packing material (,u indicates it is of low diameter, IO ,u) developed by Waters Associates’, permits the separation of compounds of small molecular size by highperformance liquid chromatography. Tliis study was aimed at developing a GPC method that is applicable to essential oils. Little worlc has been reported on tile separation of essential oils or terpenic compounds. Waters Associates2 reported tile analysis of the essential oils anise, cojeput, cedarwood, rose and wormwood using a Porasi! column with cllloroform. Recently, Nakayama et a/.j reported tile separation of mono- and sesquiterpene compounds by liquid chromatography using a Hitaclli 3010 gel column wit!1 methanol, rl-hexane and methanol-water. The purpose oftllis paper is to indicate the possibility of using liquid chromatograpliy for the analysis of essential oils. EXPERIMENTAL Appara ms

A Waters Ass. Mode! ALC202 liquid chromatograpll was used, with an M6000 pumping system. Injections were made wit11 a Waters Ass. Mode! U6K universa! injector and detection was carried out wit!1 a UV monitor at 254 nm or wit11 a Waters Ass. Mode! R401 refractive index detector. A PBondapak Cl8 column (300 x 4 mm) was used for analysis. For GPC analysis, a 300 mm x 9.52 mm O.D. x 7.6 mm I.D. ,uStyrage! column, made of seamless stainless-steel tubing, was used. Essetirial

Oils

Tile essential oils of Litrdctw ut~~belkrra and L. sericen were obtained by steam distillation of tile fresh leaves. Tile physical properties of two essential oils were as follows: L. utt~belkt~a, dz5. 0.8925, I+’ 1.4658, a:. - 17”; L. ser’icea, di5 0.9736. rig 1. 4955, ag i-34 . I o.

NOTES

259

RESULTS

Fig. 1 shows the liquid chromatograms of the essential oils of the two Laurama species obtained by using a PBondapak Cl8 column with methanol-water (I :l). The essential oils were separated completely into more than 20 peaks.

(a)

TIME(MIN)

(b)

1

JL

"V

Ax3

5 % B d

i;_,-I_._, lb

2b

3b

4b

5'0

$0

70

TIHE(Mlf4)

Fig. I, Separation of csscntial oils on a PBondapak Cl8 column anol-water (I : I): flow-rate, I ml/min. (a) L. ronbellata Thunb.;

(300 x 4 mm). Mobile phase, mcth(b) L. scrlcea var. glabruta Blume.

NOTES (a)

0

10

5

15

20

TIMB(MIN)

Fig. 2. CPC analysis of csscntial oils on a //Styrage column of dimensions 300 x 9.52 mm 0.D (1 x 10’ A, 1 x 500 .k 2 x 100 A). Mobile phase, tetrahydrofuran; flow-rate, 4 ml/min. (a) L. ~ttddla~a Thunb.: (b) L, sericea var. glahrara Blume. Peaks: A, monoterpene hydrocarbon (mol. wt. 136): B, monoterpcnealcohol (mol. wt. 154): C, monotcrpenc acetate (mol. wt. 196) and sesquiterpene hydrocarbon (mol. wt. 204): D, scsquitcrpcne alcohol and ketone (mol. wts. 220 and 218).

Gel permeation chromatograms of the essential oils are shown in Fig. 2, indicating a separation into at least five peaks. These separations were obtained in less than IS min using a ,&tyragel column (packing consisting of one 103-A column, one 500-A column and two 100-A columns). REFERENCES R. V. Vivilccchia. 99 (1974) 407.

R. L. Cotter.

R. J. Limpcrt,

N. 2. Thimot

Applicatiort Higlrli.~ltts,No. AH 313, (Essctrtiaf Oils), Waters

1974. M. Nakayama, 1 (1973) 2314.

M. Hiraoka. ’

A.

Matsuo

and S. Hayashi,

and J. N. Little, J. Clrrornntogr,, Associates,

Framingham,

Mass.,

J. Clrenr. Sot. Jap. (Clrcm. Ittrf. Clrent.),