Chemistry Reference
In-Depth Information
NMR peak parking
valve for stopped-
flow measurements
Injection
valve
Capillary
HPLC
pump
HPLC
capillary
column
CapLC
RF
Transfer capillary
(50 μm ID)
NMR
Bruker AMX 600
UV detection
Bischoff lambda 1010
HPLC pump
waters
FIGURE 4.6
Instrumental setup for capillary HPLC-NMR coupling. (From Hentschel, P. et al.,
J.
Chromatogr. A
, 285, 2006. With permission.)
OH
Lutein
HO
OH
Zeaxanthin
HO
O
Canthaxanthin
O
β-carotene
Lycopene
FIGURE 4.7
Structures of important carotenoids: (all-
E
) lutein, (all-
E
) zeaxanthin, (all-
E
) canthaxanthin,
(all-
E
) b-carotene, and (all-
E
) lycopene.
14/14
′
6.22 ppm) are doublets (integration value two for each doublet). The signals of protons 8/8
′
(6.07/6.09 ppm) together with the protons 10/10
(6.07/6.09 ppm) and 7 (6.06 ppm) overlap to yield
a multiplet (integration value of i ve). In comparison to proton 7 (6.06 ppm) proton 7
′
is shifted to
higher i eld (5.39 ppm) because of the shift of the double bond in the corresponding ionone ring.
The chemical shifts of the olei nic protons from the centrosymmetric (all-
E
) zeaxanthin are very
similar to the chemical shifts of (all-
E
) lutein except for proton 7
′
′
. The resonances of protons 11/11
′
(6.65 ppm) and of protons 15/15
′
(6.62 ppm) show a multiplet with an integration value of four. The
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