Presented at the Liquid Chromatography-Isotope Ratio Mass Spectrometry Users Meeting, held 23–24 November 2010 at the University of Oxford, Oxford, UK.
Liquid chromatography/isotope ratio mass spectrometry measurement of δ13C of amino acids in plant proteins†
Article first published online: 26 SEP 2011
Copyright © 2011 John Wiley & Sons, Ltd.
Rapid Communications in Mass Spectrometry
Volume 25, Issue 20, pages 2981–2988, 30 October 2011
How to Cite
Lynch, A. H., McCullagh, J. S. O. and Hedges, R. E. M. (2011), Liquid chromatography/isotope ratio mass spectrometry measurement of δ13C of amino acids in plant proteins. Rapid Commun. Mass Spectrom., 25: 2981–2988. doi: 10.1002/rcm.5142
- Issue published online: 13 SEP 2011
- Article first published online: 26 SEP 2011
- Manuscript Accepted: 13 JUN 2011
- Manuscript Revised: 9 JUN 2011
- Manuscript Received: 8 APR 2011
In archaeological studies, the isotopic enrichment values of carbon and nitrogen in bone collagen give a degree of information on dietary composition. The isotopic enrichments of individual amino acids from bone collagen and dietary protein have the potential to provide more precise information about the components of diet. A limited amount of work has been done on this, although the reliability of these studies is potentially limited by fractionation arising through hydrolysis of whole plant tissue (where reaction between amino acids and carbohydrates may occur) and, for certain amino acids, the use of derivatives (particularly trifluoroacetyl derivatives) for gas chromatography/isotope ratio mass spectrometry (GC/IRMS) analysis. The present study takes the approach of extracting the protein components of plant tissues before hydrolysis and using liquid chromatography/isotope ratio mass spectrometry (LC/IRMS), which does not require derivatisation, for measurement of the isotopic enrichment of the amino acids. The protocol developed offers a methodology for consistent measurement of the δ13C values of amino acids, allowing isotopic differences between the individual amino acids from different plant tissues to be identified. In particular, there are highly significant differences between leaf and seed protein amino acids (leaf minus grain) in the cases of threonine (−4.1‰), aspartic acid (+3.5‰) and serine (−3.2‰). In addition to its intended application in archaeology, the technique will be of value in the fields of plant sciences, nutrition and environmental food-web studies. Copyright © 2011 John Wiley & Sons, Ltd.