A High-Resolution NMR Approach Combined to MALDI-TOF-MS to Estimate the Positional Distribution of Acyl-Linked Unsaturated Fatty Acids in Triacylglycerols
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Triacylglycerols (TAGs) are the most abundant constituents of vegetable oils and adipose tissues. TAG analysis is even, nowadays, challenging because the presence of three (often different) fatty acyl residues leads to many different, regioisomeric species. While the overall fatty acyl composition of TAG can be determined by gas chromatography/mass spectrometry (GC/MS), all positional information is completely lost by this approach. Therefore, GC/MS is often replaced or combined with LC/MS that provides information (by MS/MS) which fatty acyl residues are present in a given TAG and sometimes also about the location at the glycerol backbone. Since TAGs are normally available in huge amounts, the comparably low sensitivity of NMR is not a major issue. We show that high-resolution 13C NMR spectroscopy is an excellent method to determine the overall fatty acyl composition and the positions of the related (unsaturated) fatty acyl residues in a given TAG molecule. These data will be compared with MALDI-TOF MS data of the same vegetable oil samples. Although the 13C NMR method is particularly applicable to unsaturated TAG, this approach can be regarded as a significant methodological progress in this field.
KeywordsTriacylglycerols Regioisomers Vegetable oils 1H NMR 13C NMR spectroscopy MALDI-TOF mass spectrometry
This study was supported by the German Research Council (DFG Schi 476/12-2 and Schi 476/16-1 and SFB 1052/Z3). We would also like to thank all our colleagues who helped us in performing the related experiments. We are particularly indebted to Bruker Daltonics (Bremen) and Merck Millipore (Darmstadt) for the continuous and generous support.
Compliance with Ethical Standards
This study was funded by the German Research Council (in particular, grant number SFB 1052/B6).
Conflict of Interest
Andrej Meusel declares that he has no conflict of interest. Yulia Popkova declares that she has no conflict of interest. Dirk Dannenberger declares that he has no conflict of interest. Jürgen Schiller declares that he has no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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