LC-UV-solid-phase extraction-NMR-MS combined with a cryogenic flow probe and its application to the identification of compounds present in Greek oregano

被引:170
作者
Exarchou, V
Godejohann, M
van Beek, TA
Gerothanassis, IP
Vervoort, J
机构
[1] Wageningen Univ, Biochem Lab, NL-6703 HA Wageningen, Netherlands
[2] Univ Ioannina, Dept Chem, Sect Organ Chem & Biochem, GR-45110 Ioannina, Greece
[3] Bruker Biospin GMBH, D-76287 Rheinstetten, Germany
[4] Wageningen Univ, Nat Prod Chem Grp, Organ Chem Lab, NL-6703 HB Wageningen, Netherlands
关键词
D O I
10.1021/ac0347819
中图分类号
O65 [分析化学];
学科分类号
070302 ; 081704 ;
摘要
Structure elucidation of natural products usually relies on a combination of NMR spectroscopy with mass spectrometry whereby NMR trails MS in terms of the minimum sample amount required. In the present study, the usefulness of on-line solid-phase extraction (SPE) in LC-NMR for peak storage after the LC separation prior to NMR analysis is demonstrated. The SPE unit allows the use of normal protonated solvents for the LC separation and fully deuterated solvents for flushing the trapped compounds to the NAIR probe. Thus, solvent suppression is no longer necessary. Multiple trapping of the same analyte from repeated LC injections was utilized to solve the problem of low concentration and to obtain 2D heteronuclear NMR spectra. In addition, a combination of the SPE unit with a recently developed cryoflow NMR probe and an MS was evaluated. This on-line LC-UV-SPE-NMR-MS system was used for the automated analysis of a Greek oregano extract. Combining the data provided by the UV, MS, and NMR spectra, the flavonoids taxifolin, aromadendrin, eriodictyol, naringenin, and apigenin, the phenolic acid rosmarinic acid, and the monoterpene carvacrol were identified. This automated technique is very useful for natural product analysis, and the large sensitivity improvement leads to significantly reduced NAIR acquisition times.
引用
收藏
页码:6288 / 6294
页数:7
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