| PreCon-IRMS测定土壤游离氨基酸态氮稳定同位素丰度 |
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| 引用本文： | 贺珍,袁红朝,张丽萍,耿梅梅,许丽卫,陈闻,彭灿,王久荣. PreCon-IRMS测定土壤游离氨基酸态氮稳定同位素丰度[J]. 质谱学报, 2022, 43(2): 220-227. DOI: 10.7538/zpxb.2021.0061 |
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| 作者姓名： | 贺珍 袁红朝 张丽萍 耿梅梅 许丽卫 陈闻 彭灿 王久荣 |
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| 作者单位： | 中国科学院亚热带农业生态过程重点实验室，湖南 长沙410125 |
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| 摘 要： | 土壤氮大部分为有机氮,大分子类有机氮-蛋白质转化成可溶性氨基酸态氮是土壤氮循环的关键过程和土壤氮素有效性的主要限制因子,其中氨基酸态氮消耗速率在研究土壤肥力、生物机制等方面有着重要的指示作用.本研究建立了一种蒸馏结合化学转化N2 O产生法的氨基酸态氮稳定同位素丰度测定前处理方法,并结合气体预浓缩装置与稳定同位素质谱仪(...
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| 关 键 词： | 土壤游离氨基酸 稳定同位素质谱 氮同位素 蒸馏 化学转化N2O法 |
Nitrogen Stable Isotope Determination in Soil Free Amino Acid N by PreCon-IRMS System |
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| HE Zhen,YUAN Hong-zhao,ZHANG Li-ping,GENG Mei-mei,XU Li-wei,CHEN Wen,PENG Can,WANG Jiu-rong. Nitrogen Stable Isotope Determination in Soil Free Amino Acid N by PreCon-IRMS System[J]. Journal of Chinese Mass Spectrometry Society, 2022, 43(2): 220-227. DOI: 10.7538/zpxb.2021.0061 |
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| Authors: | HE Zhen YUAN Hong-zhao ZHANG Li-ping GENG Mei-mei XU Li-wei CHEN Wen PENG Can WANG Jiu-rong |
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| Affiliation: | Key Laboratory of Agro ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China |
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| Abstract: | The majority of soil nitrogen is closely associated with soil organic matter, the cleavage of high molecular weight organic N such as protein to smaller soluble compounds (e.g amino acids) is a key step in the terrestrial N cycle. Therefore, as amino acids occupy a central position in understanding the N biogeochemical cycling processes and ecosystem functions, using natural abundance level isotopic information of amino acids or the heavier isotope 15N as a tracer helps advance the knowledge of soil fertility and its biological mechanism. Currently isotope pool dilution approach and compound specific isotope analysis (CSIA) approaches have been successful established to measure amino acid in soils. However, both of them need large sample requirements and labor consuming isolation procedures for the isotope analysis of amino acids. In this study, a novel distillation chemical conversion N2O approach based on the 15N analysis by the oxidation of amino groups to NO2- and further reduction to N2O was described, followed by PreCon isotope ratio mass spectrometry (PreCon-IRMS). Sample preparation was carried out by our self-developed device automatic micro-nitrogen conversion N2O generating device, allowing either helium (He) purging of gas or liquid charging from a range of suitable, airtight bottles. The reaction conditions for the N2O production were explored and optimized, including the hypobromite concentration, NaOH concentration, and amino acid mixtures concentration. The nitrogen stable isotope abundance in standard solutions of amino acid mixtures with different concentrations and 15N abundance, as well as the nitrogen stable isotope abundance of free amino acids in tested soil were analyzed by using the newly developed pretreatment method combined with the PreCon IRMS system. The results showed that the developed method coupled IRMS analytical system was able to measure the 15N abundance in all standard solutions and soil extracts with good precision of 02% 08% (CV<1%) without isotope fractionation at the limits of quantification as 0.5 μmol. This method has a great advantage compared with current approaches avoid time-consuming isolation and toxic reagents requirement. The pretreatment analysis time is short, and the soil samples with the amino acid concentration of nmol grade can be detected. |
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| Keywords: | soil free amino acid isotope ratio mass spectrometry (IRMS) nitrogen isotope distillation chemical conversion N2O method |
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