Abstract:

【Objective】 To measure the stable carbon and nitrogen isotope composition of amino acids in wheat grain by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). 【Method】 The N-pivaloyl-isopropyl (NPP) derivatives of the protein amino acids, which hydrolyzed with 6M HCl in wheat grain Linfen 50744, and standard amino acids were measured by GC-C-IRMS.【Result】 Analysis of stable carbon and nitrogen isotope composition of N-pivaloyl-isopropyl (NPP) amino acid standard esters shows the mean reproducibility of δ13C is 0.47‰ and δ15N is 0.28‰. Good results can be got as less isotope fractionation is observed in this study. The δ13C values of NPP derivatives were from -28.7‰ to -34.7‰, and the δ15N values of NPP derivatives were -6.2‰ to 9.5‰. Amino acids can be divided into two categories according to δ13C, and three categories according to δ15N by hierarchical cluster analysis. 【Conclusion】 It is feasible to determine the composition of stable carbon and nitrogen isotope of amino acids in wheat with NPP amino acid esters by GC-C-IRMS, which will make great significance to reveal the difference of metabolism and synthesis of amino acids under adverse environment.

Key words: GC-C-IRMS, NPP amino acid esters, δ13C, δ15N