GC-MS for determining soil amino acid chiral isomer isotope enriching rate

Abstract

The invention relates to soil nitrogen cycle, in particular to a method for measuring isotopic enrichment rate of chiral isomers of hydrolysate amino acids in soil by using gas chromatography-mass spectrum. The method comprises the following steps of: selecting carbon and nitrogen compounds with isotope abundance of 50% to 100% to carry out stable isotope added sample culture experiment; (2) hydrolyzing soil samples respectively with superfluous HCl, separating the hydrolysate with cation exchange resin to obtain hydrolysate amino acids in soil, evaporating the extractive solution to obtain dry sample, and producing derivatives from the dry sample by pentafluoropropionic anhydride-isopropyl alcohol method; (3) separating the derivatives by gas chromatography, and measuring the mass spectral peak area and isotope ion peak area of chiral isomers of each hydrolysate amino acid; and (4) representing the change of relative abundance of isotopes of chrial isomers of amino acids resulting from whether inorganic <15>N or <13>C or glucose by APE, and representing the velocity for synthesizing amino acid nitrogen from NH4<+> or NO3<-> and the velocity for synthesizing amino acid carbon fromglucose by the ratio of APE to culture time.

Description

technical field [0001] The invention relates to soil nitrogen cycle research, in particular to a method for measuring soil hydrolyzed amino acid chiral isomer isotope enrichment rate by gas chromatography-mass spectrometry. Background technique [0002] The amount of amino acids in soil was first determined by the acid hydrolysis-distillation method in soil organic nitrogen speciation analysis (Lu Rukun, Soil Agricultural Chemical Analysis Methods, pp152-156, China Agricultural Science and Technology Press, 1999), but only the total amount of amino acids can be calculated; Gas chromatography can effectively separate 15 chiral isomers of amino acids and quantify them one by one, but its quantitative characteristics are static, reflecting the accumulation of amino acids after a combination of various factors, and cannot reflect the concentration of chiral isomers of amino acids. Dynamic changes (W. Amelung, X. Zhang. 2001. Determination of amino acid enantiomers in soils. Soil...

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Problems solved by technology

[0002] The amount of amino acids in soil was first determined by the acid hydrolysis-distillation method in soil organic nitrogen speciation analysis (Lu Rukun, Soil Agricultural Chemical Analysis Methods, pp152-156, China Agricultural Science and Technology Press, 1999), but only the total amount of amino acids can be calculated; Gas chromatography can effectively separate 15 chiral isomers of amino acids and quantify them one by one, but its quantitative characteristics are static, reflecting the accumulation of amino acids after a combination of various factors, and cannot reflect the concentration of chiral isomers of amino acids. Dynamic changes (W. Amelung, X. Zhang. 2001. Determination of amino acid enantiomers in soils. Soil Biology & Biochemistry 33: 553-562)

Gas chromatography-combustion-isotope ratio mass spectrometry can distinguish the natural isotopic abundance changes of amino acid chiral isomers, but the degree of isotopic discrimination is small and cannot be adjusted, so it is not suitable for the cycle transformation of soil nutrients, and the determination cost is high and easy Isotope pollution to the instrument, and the isotope discrimination ratio deviation caused by the sample processing process cannot overcome the quantitative correction (Amelung, W., Brodowski, S., 2002.In vitro quantification of hydrolysis-induced racemization of amino acid enantiomers in environmental samples using deuterium label

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