○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
16
Figure 18
The Rt-
β
DEXsm column is optimum
for the separation of (+/-)
α
- and
β
-pinene, limonene, and menthone
in peppermint oil.
Figure 19A
Analyze spearmint oil on the
Rt-
β
DEXsm column to obtain
maximum separation of (+/-)
α
-
and
β
-pinene, limonene, and
menthone enantiomers
.
15
min. 10
20 25 30 35 40 45
1
2
3
3
4
1. (-/+)
α
-pinene
2. (+/-)
β
-pinene
3. (-/+) limonene
4. (+/-) menthone
5. (+/-) menthol (no sep.)
5
{
{
{
15
min. 10
20 25 30 35 40 45
1.
α
-pinene
2.
β
-pinene
3. limonene
4. menthone
5. menthol (no sep.)
6. carvone (no sep.)
1
2
33
4
5
{
{
{
6
Figure 19B
The optical isomers of carvone best
separate on the Rt-
β
DEXsa column.
30m, 0.32mm ID, 0.25µmRt-
β
DEXsm (cat.# 13104);
Oven temp.:
40°C (hold 1min.) to
200°C@ 2°C/min. (hold 3min.);
Carrier gas:
helium; 60cm/sec.;
Detector:
MSD set @ 220°C
30m, 0.32mm ID, 0.25µmRt-
β
DEXsm (cat.# 13104);
Oven temp.:
40°C (hold 1min.) to
200°C@ 2°C/min. (hold 3min.);
Carrier gas:
helium; 60cm/sec.;
Detector:
MSD set @ 220°C
Midwestern
Spearmint
(d)
(l)
Racemic
Carvone
Standard
(d)
(l)
min. 38
39
40
30m, 0.32mm ID, 0.25µm Rt-
β
DEXsa
(cat.# 13108);
Oven temp.:
40°C
(hold 1min.) to 200°C@ 2°C/min.;
Carrier gas:
helium; 60cm/sec. set @ 40°C;
Detector:
MSD set @ 220°C
Peppermint Oil provided
byAM Todd.
Spearmint Oil provided
byAM Todd.
PeppermintOil
○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○
TheRt-
β
DEXsmcolumn isoptimum for theseparationof (+/-)
α
-and
β
-pinene,
limonene andmenthone. Since menthone andmenthol enantiomers are ma-
jor constituents of peppermint oil, reducing the sample size to prevent over-
loading of these components and provide better enantiomeric resolutionmay
be necessary.
Analternative solution is touse anRt-
β
DEXspas a secondary column since it
provides better resolution of menthol. However, do not use this column in a
dual columnsystemwithanRt-
β
DEXsm. Theminimum temperaturesof these
phases differ by 20°C, which wouldminimize volatile terpene separation on
the Rt-
β
DEXsm (
Figure 18
).
SpearmintOil
○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○
The Rt-
β
DEXsm column yieldsmaxi-
mum separation of (+/-)
α
- and
β
-
pinene, limonene and menthone
enantiomers in spearmint oil. The
enantiomeric ratios of the primary
chiral constituents in an artificial
spearmintoil canbeseen in thechro-
matogram shown in
Figure 19A
.
Although the optical isomers of
carvone best separate on the Rt-
β
DEXsa column,
α
-pinene and li-
monene donot. For the separation of
carvone, use a dual column system
comprised of 30-meter Rt-
β
DEXsm
and Rt-
β
DEXsa columns, since both
have aminimum operating tempera-
ture of 40°C.
Figure 19B
compares
carvone in natural sources of spear-
mint oil to a racemic standard on the
Rt-
β
DEXsa column.
min. 38
39
40
