Application Note
Purification of Carvone in Spearmint Oil using SFC with PDA and
FTIR Dual-Monitoring
Introduction
Terpenes in essential oils are easily oxidized
and can cause a decrease in the flavor in foods.
Removal of Terpenes is commonly practiced
in perfume industry to yield higher quality oils.
Natural spearmint oilcontains l-limonene that
is quite unlike d-limonene, the aroma is not
reminiscent of citrus but of a light, clean Terpene
hydrocarbon fragrance. Conventionally, Terpenes
are removed using vacuum distillation. However,
it is difficult to monitor the fractionation process
in real-time during this process.
Jasco SF-2000 SFC system
We used SFC with a PDA detector and an
FTIR spectrometer as a dual monitoring system
to enable selective monitoring of the target
compound Carvone in real time during elution
and fractionation. The PDA provides broad
information on the separation, but cannot
differentiate between limonene and Carvone.
Keyword: Terpenes, essential oil purification, Spearmint Oil,
Limonene, Carvone, CO2, SFC, FTIR, Enrichment HPLC-FTIR
JASCO INC.
28600 Mary’s Court, Easton, MD 21601 USA
Tel: (800) 333-5272, Fax: (410) 822-7526
Application Library: http://www.jascoinc.com/applications
Application Note
Purification of Carvone in Spearmint Oil
2/4
Table 1. Constituents of Spearmint Oil
Component
Percent Content
α-Pinene
0.40
Β-Pinene
0.51
Limonene
20.80
Β-Borbonene
0.80
Octanol
0.61
Mentol
1.03
Dihydrocarbeol
2.71
Dihydrocarvyl
1.92
present in caraway oil while l-carvone is present in spearmint oil.
Carvone
59.70
They are easily differentiated by the nose.d-limonene is present
Cis-, Trans-dihydrocarvone
3.65
Mentone
1.50
Total
93.63
A
B
l-carvone
C
d-carvone
D
l-limonene
d-limonene
Figure 1. Structures of Carvone and Limonene. d-carvone is
in citrus oils while l-limonene is present in spearmint oil, pine oil, etc.
It is desirable to remove l-limonene from spearmint oil.
Figure 2. UV and IR Spectra of Limonene and Carvone Standards.
Figure 2, Limonene and Carvone have very similar UV spectra, but show differences in the IR. Co-elution
in the chromatogram detected using UV as shown in figure 3 and 4 illustrates the inability of using UV to
trigger fraction collection.
Figure 5 shows IR chromatograms at two different wave number ranges and the fractions collected using
those chromatograms. A Carvone standard and Spearmint oil were separated using HPLC and fractions 1
and 2 were compared to confirm the separation and purity as seen in Figure 6.
JASCO INC.
28600 Mary’s Court, Easton, MD 21601 USA
Tel: (800) 333-5272, Fax: (410) 822-7526
Application Library: http://www.jascoinc.com/applications
Copyright © JASCO Corporation
Application Note
Purification of Carvone in Spearmint Oil
3/4
SFC Conditions
CO2 Flow rate:
3mL/min
Temperature:
40°C
Pressure:
150 bar
Sample Amount:
Spearmint Oil 200uL
Column:
SFCpak SIL-5
(4.6mm x 250mm)
Detector:
MD-2010
FTIR-4200 with ATR
PRO 400-L : Flow cell
Figure 3. PDA Contour Plot of Spearmint Oil. The PDA could not differentiate limonene from carvone due to apparent co-elution.
Therefore fraction timing could not be set based on the PDA.
Terpenes including Limonene
Carvone and co-eluting compounds
Figure 4. SFC Chromatograms of Spearmint Oil by PDA Detection.
JASCO INC.
28600 Mary’s Court, Easton, MD 21601 USA
Tel: (800) 333-5272, Fax: (410) 822-7526
Application Library: http://www.jascoinc.com/applications
Copyright © JASCO Corporation
Application Note
Purification of Carvone in Spearmint Oil
4/4
Figure 5. IR Chromatogram of Spearmint Oil used for Fractionation.
Carvone
Figure 6. HPLC Chromatograms.
HPLC Conditions: Column: Crestpak C18S, Mobile Phase: CH3CN/H2O 60/40
Flow rate: 1.0mL/min, Column Temperature: 40°C.
Conclusions
The carvone content in the original spearmint oil (62.7%) was successfully enriched to 89.1%. During the
fractionation process the limonene peak was clearly detected using FTIR and was easily removed as
fraction 1. HPLC was used to analyze the purity of the two fractions and confirmed the removal limonene
from the spearmint oil.
JASCO INC.
28600 Mary’s Court, Easton, MD 21601 USA
Tel: (800) 333-5272, Fax: (410) 822-7526
Application Library: http://www.jascoinc.com/applications
Copyright © JASCO Corporation