RestekCorporation • (800)356-1688 • (814)353-1300 •
Figure3
TheRt-
g
DEXsa
™
columnprovides excellent chiral selectivity for bothmethyl- and ethyl-3-hydroxybutyrate
in the flavor extracts of grape juice andwhite grape juice.
30m, 0.32mm ID, 0.25µmRt-
g
DEXsa
™
(cat.# 13112) 10µL direct injection of grape juice (Fig. 3a) andwhite grape juice (Fig. 3b) using a 4mm open-top
Uniliner
®
sleeve (cat.# 20843).
Oven temp.:
40°C (hold 1min.) to 230°C@ 2°C/min.;
Inj. / det. temp.:
200°C/230°C;
Carrier gas:
H
2
;
Linear velocity:
80cm/sec. set @ 40°C.
min. 20
22
24
26
28
1. (S)-(+)-methyl-3-hydroxybutyrate
2. (R)-(–)-methyl-3-hydroxybutyrate
3. (S)-(+)-ethyl-3-hydroxybutyrate
4. (R)-(–)-ethyl-3-hydroxybutyrate
1
2
3
4
1
2
3
4
30
min. 20
22
24
26
28
30
Fig. 3a - grape juice
Fig. 3b -whitegrape juice
Figure2
Beta-cyclodextrin columns donot provide optimum separationofmethyl- and ethyl-3-hydroxy butyrate.
30m, 0.32mm ID, 0.25µm a) Rt-
b
DEXm
™
; b) Rt-
b
DEXsm
™
; and c) Rt-
b
DEXsa
™
columns (cat.#s 13101, 13104, and 13108 respectively). 1.0µL split
injection of methyl- and ethyl-3-hydroxybutyrate;
On-column concentration:
~150ng/enantiomer;
Oven temp.:
40°C (hold 1min.) to 200°C@
2°C/min.;
Inj. / det. temp.:
200°C/230°C;
Carrier gas:
H
2
;
Linear velocity:
80cm/sec. set @ 40°C;
Split ratio:
25:1.
1. (S)-(+)-methyl-3-hydroxybutyrate
2. (R)-(–)-methyl-3-hydroxybutyrate
3. (S)-(+)-ethyl-3-hydroxybutyrate
4. (R)-(–)-ethyl-3-hydroxybutyrate
B) TheRt-
b
DEXsm
™
column exhibits poor
enantiomeric separation.
C) TheRt-
b
DEXsa
™
column exhibits improved
enantiomeric separation.
A) TheRt-
b
DEXm
™
column exhibits no enantiomeric selectivity.
1
2
3
4
min.
20
22
14
16
18
1
2 3
4
min. 14
16
18
min. 8
10
12
14
1,2
3,4
