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13
Figure 15A
Linalool and linalyl acetate have
symmetrical peak shapes and
excellent chiral separation on the
Rt-
β
DEXse column at 25ng per
component on-column.
linalool
min. 30
35
40
linalyl acetate
linalool
min. 30
35
40
linalyl acetate
linalool
min. 30
35
40
linalyl acetate
Figure 15C
Excessive overload of chiral com-
pounds on cyclodextrin columns
results in extreme peak tailing and
complete loss in resolution.
Figure 15B
Linalool shows signs of overload
with slight peak tailing, and linalyl
acetate has a small loss in
resolutionwhen sample load is
increased to160ng.
R S
R S
R
S
R
S
R S
R,S
30m, 0.32mm ID, 0.25µm
Rt-
β
DEXse (cat.# 13106)
Oven temp.:
40°C (hold 1min.) to 200°C
@ 2°C/min.;
Carrier gas:
hydrogen;
80cm/sec. set @ 40°C;
Detector:
FID set @ 220°C
30m, 0.32mm ID, 0.25µm
Rt-
β
DEXse (cat.# 13106)
Oven temp.:
40°C (hold 1min.) to 200°C
@ 2°C/min.;
Carrier gas:
hydrogen;
80cm/sec. set @ 40°C;
Detector:
FID set @ 220°C
30m, 0.32mm ID, 0.25µm
Rt-
β
DEXse (cat.# 13106)
Oven temp.:
40°C (hold 1min.)
to 200°C@ 2°C/min.;
Carrier gas:
hydrogen;
80cm/sec. set @ 40°C;
Detector:
FID set @ 220°C
Overloading
andTailing
○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○
Some chiral compounds show over-
loading at lower concentrations than
achiral compounds.Onereason is the
different amounts of cyclodextrin (5-
50%) dissolved in the stationary
phase. Unlike the classical fronting
peaks of normal stationary phases,
the characteristic of an overloaded
peak on cyclodextrin stationary
phases is indicatedby a tailing peak.
Overloading chiral compounds re-
sults in loss of resolution, evenwhen
column capacity has not been ex-
ceeded.
Figure 15A
shows the enan-
tiomeric separations of linalool and
linalyl acetateon theRt-
β
DEXse. The
amount for each component in the
column is about 25 ng.
Figure 15B
shows the same components at a
higherconcentrationof160ngon-col-
umn. Note that the linalool enanti-
omersarebeginning to tail, and there
is a small loss in chiral resolution for
linalylacetate.Even though themaxi-
mum sample capacity for 0.32mm ID
capillary columns is normally 400-
500ng per component, the peak
shapes of chiral compounds indicate
overload at one-third of the sample
amount. Again, there is much less
cyclodextrin for which a chiral com-
pound can interact.
Figure 15C
shows pronounced overloading of
these compounds at 5µg on-column.
Extreme tailing and complete loss in
resolution are the result.
