Hyphenation of high performance liquid chromatography with nuclear magnetic resonance spectroscopy for the characterization of beta-carotene isomers employing a C-30 stationary phase
S. Strohschein et al., Hyphenation of high performance liquid chromatography with nuclear magnetic resonance spectroscopy for the characterization of beta-carotene isomers employing a C-30 stationary phase, J PHARM B, 21(3), 1999, pp. 669-677
The hyphenation of HPLC together with NMR spectroscopy proves advantageous
for the structure elucidation of oxidation- and UV-sensitive compounds such
as beta-carotene isomers. In the closed-loop HPLC-NMR system, degradation
or isomerization of separated compounds is largely hindered. With the help
of 3-mu m C-30 stationary phases a better separation efficiency towards the
different beta-carotene cis/trans isomers could be obtained in comparison
to a 5-mu m material, resulting in sharper peaks and a better resolution of
all compounds. This effect greatly faciliated the structure determination
of the isomers by HPLC-NMR coupling. Due to the introduction of a superior
stationary phase, the structure of seven cis-isomers of beta-carotene could
thereby be determined employing the stopped-flow HPLC-H-1-NMR mode. (C) 19
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