title: [Determination of 13C enrichment in soil amino acid enantiomers by gas chromatogram/mass spectrometry].
abstract: The transformation and renewal of amino acid enantiomers is of significance in indicating the turnover mechanism of soil organic matter. In this paper, a method of gas chromatogram/mass spectrometry combined with U-13 C-glucose incubation was developed to determine the 13C enrichment in soil amino acid enantiomers, which could effectively differentiate the original and the newly synthesized amino acids in soil matrix. The added U-13 C-glucose was utilized rapidly to structure the amino acid carbon skeleton, and the change of relative abundance of isotope ions could be determined by mass spectrometry. The direct incorporation of U-13 C glucose was estimated by the intensity increase of m/z (F + n) to F (F was parent fragment, and n was the carbon number in the fragment), while the total isotope incorporation from the added 13C could be calculated according to the abundance ratio increment summation from m/z (Fa + 1) through (Fa + T) (Fa was the fragment containing all original skeleton carbons, and T was the carbon number in the amino acid molecule). The 13C enrichment in the target compound was expressed as atom percentage excess (APE), and that of D-amino acid needed to be corrected by the coefficient of hydrolysis-induced racemization. The 13C enrichment reflected the carbon turnover velocity of individual amino acid enantiomers, and was powerful to investigate the dynamics of soil amino acids.
authors.affiliation: Key Laboratory of Terrestrial Ecological Process, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China. hehongbo@iae.ac.cn
authors.forename: Hong-Bo
authors.initials: HB
authors.lastname: He
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Xue-Li
authors.initials: XL
authors.lastname: Ding
authors.forename: Zhen
authors.initials: Z
authors.lastname: Bai
authors.forename: Ning
authors.initials: N
authors.lastname: Liu
authors.forename: Xu-Dong
authors.initials: XD
authors.lastname: Zhang
mesh_terms: D000596:Amino Acids / Q000032:analysis* / Q000737:chemistry; D002247:Carbon Isotopes / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D012987:Soil / Q000032:analysis*; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D002247:Carbon Isotopes; D012987:Soil