Biomedical Engineering Reference
In-Depth Information
traces of impurities in samples of
dextro
-brompheniramine. Zhong and Yeung [188]
designed a capillary array system for combinatorial chiral separations. The system
consisted of 96 capillaries, whereby the outlet ends of every eight capillaries were
bundled together. Thereby in 12 bundles, 8 compounds can be tested in the same run
at 12 different separation conditions. Using neutral and sulfated CDs as chiral selec-
tors with different buffers, for 49 out of 54 compounds tested, the optimal separation
conditions could be found within short time. Male and Luong [189] designed a CE
system equipped with an array of microfabricated interdigitated platinum electrodes.
The system was applied to the simultaneous chiral analysis of epinephrine, norephed-
rine, and isoproterenol, using heptakis(2,6-di-
O
-methyl)-
-cyclodextrin as a chiral
selector. The interdigitated electrode chip served as an amplii cation/detection sys-
tem and consisted of an array of seven electrodes at oxidizing potential to oxidize
the analytes and a detector electrode set at reducing potential. Thereby fouling of the
detection electrode is avoided. Henley et al. [190] developed a system making use
of a counterl ow produced by a pump in the direction opposite to the electrokinetic
migration of the analyte. Using
β
-CD as a chiral selector, an improvement in resolu-
tion was obtained in this counterl ow system for a series of drugs. Lee et al. [191]
β
Event
Inlet
Outlet
Detector
BGE
-
-
BGE
(a)
Inject
-
-
-
-
BGE pH 2.0
-
-
-
-
-
-
Sample in
water, pH 6.0
EOF
-30 kV
BGE
BGE
-
-
-
-
(b)
-
-
-
BGE pH 2.0
-
-
-
-
No current
+
-
-
Sample in
water, pH 6.0
EOF
-
-
BGE
BGE
-30 kV
-
-
BGE pH 2.0
-
(c)
+
-
-
Current ~30 μA
Sample in
water, pH 6.0
L D
-30 kV Chiral
BGE
-
-
BGE
(d)
BGE pH 2.0
-
-
+
-
-
separation
-
-
Sample in
water, pH 6.0
FIGURE 3.17
Schematic diagram of the pH-mediated stacking/sweeping-
S
-β-CD of
racemic CBI-amino acids. (From Kirschner, D.L. et al.,
Anal. Chem
., 79, 736, 2007. With
permission.)
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