氨基酸单体氮稳定同位素分析测试方法研究  

Study on the Compound Specific Nitrogen Stable Isotope Determination of Amino Acids

作　　者：梁建鑫 尹希杰 李玉红 林锡煌 LIANG Jian-xin;YIN Xi-jie;LI Yu-hong;LIN Xi-huang(Information and Testing Support Center,Third Institute of Oceanography,Ministry of Natural Resources,Xiamen 361005,China)

机构地区：[1]自然资源部第三海洋研究所分析测试中心,福建厦门361005

出　　处：《分析测试学报》2025年第2期334-341,共8页Journal of Instrumental Analysis

基　　金：中国地质调查局舟山海洋地质灾害野外科学观测研究站开放基金资助项目(ZSORS-22-10);自然资源部第三海洋研究所基本科研业务费项目(海三科2024010,2024014)。

摘　　要：该研究建立了一种精准测定不同样品中氨基酸含量及其氮同位素组成的方法。首先利用N-新戊酰基-O-异丙酯(NPP)对氨基酸进行衍生化,使其更适用于气相色谱分析。随后,采用气相色谱-质谱(GCMS)对大豆、土壤以及标准样品中的15种氨基酸单体进行定量分析,所有目标氨基酸均获得良好的分离效果,且在1.0~16.0μmol/L浓度范围内呈线性关系(r^(2)>0.98)。此外,利用气相色谱-燃烧-同位素比值质谱(GC-C-IRMS)对上述样品中氨基酸的氮同位素组成(δ~(15)N)进行了测定。结果表明,当进样量超过20 ng N([N_(2)^(+)]m/z 28信号强度约为150 mV)时,该方法可以获得稳定可靠的δ^(15)N值,平均精度可达0.36‰。通过与元素分析-同位素比值质谱(EA-IRMS)的结果进行比较,两种方法的测定结果高度一致(r^(2)=0.9954),表明NPP衍生化过程未引入明显的氮同位素分馏。最终测得大豆和土壤样品中各氨基酸的δ~(15)N值分别分布在10.90‰~22.32‰和-1.92‰~12.82‰之间,标准偏差分别为0.23‰~0.88‰和0.08‰~0.79‰,符合样品分析的精度要求。This study investigated a method for determining the content and nitrogen isotopic compo⁃sition of amino acids in different samples.Amino acids were derivatized using N-pivaloyl-O-isopropyl ester(NPP)and analyzed via gas chromatography-mass spectrometry(GC-MS)and gas chromatogra⁃phy-combustion-isotope ratio mass spectrometry(GC-C-IRMS).Results showed effective separation of 15 amino acid standards after NPP derivatization on GC-MS,with good linearity(r^(2)>0.98)be⁃tween concentration and peak area in the range of 1.0-16.0μmol/L.The GC-C-IRMS analysis yieldedδ15N values for the 15 amino acid standards with a precision of 0.22‰-0.76‰(n=8),com⁃parable to those obtained by elemental analysis-isotope ratio mass spectrometry(EA-IRMS),with a difference ranging from 0.15‰to 1.14‰.The strong correlation(r2=0.9954)between the two meth⁃ods suggests that the derivatization process did not introduce significant isotopic fractionation.Stable and accurateδ15N values were achieved with an injection amount greater than 20 ng N(corresponding to a[N_(2)^(+)]m/z 28 signal intensity of approximately 150 mV),resulting in an average precision of 0.36‰.Analysis of soybean and soil samples revealedδ15N values ranging from 10.90‰to 22.32‰and-1.92‰to 12.82‰,respectively,with standard deviations of 0.23‰-0.88‰and 0.08‰-0.79‰,respectively,meeting the accuracy requirements for sample analysis.

关 键 词：气相色谱-燃烧-同位素比值质谱(GC-C-IRMS) N-新戊酰基-O-异丙酯(NPP) 氨基酸 氮稳定同位素 

分 类 号：O657.63[理学—分析化学] O562.6[理学—化学]