Li Yanan, Liu Ziping, Yue Xiuquan, Jiang Shicheng
Institute of Grassland Science, School of Life Science, Northeast Normal University, Key Laboratory of Vegetation Ecology, Ministry of Education, Jilin Songnen Grassland Ecosystem National Observation and Research Station, Changchun, 130024, China.
Key Laboratory of Geographical Processes and Ecological Security of Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Changchun, 130024, China.
J Chromatogr A. 2025 Aug 30;1757:466158. doi: 10.1016/j.chroma.2025.466158. Epub 2025 Jun 22.
Amino sugars function as crucial microbial biomarkers, indicating the extent of microbial residue contributions to soil composition. Their effectiveness in tracing microbial processing of soil organic matter stems from their rarity in plant residues, their prevalence in microbial cell walls, and their remarkable stability post-cell death. The application of amino sugar-based stable isotope probing (AS-SIP) technology offers a robust method for investigating amino sugar dynamics in soils. This study advocates using signal height, as determined by gas chromatography-combustion-isotope ratio mass spectrometry (GCC-IRMS), instead of conventional metrics such as concentration or injected volume, to establish a correction factor for determining the δC value of amino sugars. The δC value referenced to gas is considered to reflect the "True value" of aldononitrile derivatives of amino sugars, as the δC value of CO is pre-calibrated via elemental analysis-isotope ratio mass spectrometry (EA-IRMS) utilizing multi-point normalization. Our proposed methodology mitigates significant analytical errors associated with δC correction during the detection of aldononitrile derivatives of amino sugars via GCC-IRMS, thereby enhancing its applicability in both natural and C-enriched amino sugar analyses. The results obtained align closely with those measured by EA-IRMS. The aldononitrile derivatives analyzed by GCC-IRMS for C-enriched glucosamine standards exhibit strong linearity up to 1000 ‰ (R² = 0.9995). No isotopic carryover effect was observed between the δC values of C-enriched and natural glucosamine standards below 500 ‰. The developed method for determining the δC values of amino sugars was successfully implemented in the analysis of soil samples.
氨基糖作为重要的微生物生物标志物，指示微生物残体对土壤组成的贡献程度。它们在追踪土壤有机质微生物分解过程中的有效性源于其在植物残体中罕见、在微生物细胞壁中普遍存在以及细胞死亡后具有显著的稳定性。基于氨基糖的稳定同位素探测（AS-SIP）技术的应用为研究土壤中氨基糖动态提供了一种强大的方法。本研究主张使用气相色谱-燃烧-同位素比率质谱法（GCC-IRMS）测定的信号高度，而非浓度或进样量等传统指标，来建立用于确定氨基糖δC值的校正因子。由于CO的δC值通过利用多点归一化的元素分析-同位素比率质谱法（EA-IRMS）进行了预校准，因此以气体为参考的δC值被认为反映了氨基糖醛腈衍生物的“真实值”。我们提出的方法减轻了通过GCC-IRMS检测氨基糖醛腈衍生物期间与δC校正相关的重大分析误差，从而提高了其在天然和富含C的氨基糖分析中的适用性。获得的结果与EA-IRMS测量的结果密切吻合。通过GCC-IRMS分析的富含C的葡萄糖胺标准品的醛腈衍生物在高达1000‰时表现出很强的线性（R² = 0.9995）。在低于500‰时，富含C和天然葡萄糖胺标准品的δC值之间未观察到同位素残留效应。所开发的测定氨基糖δC值的方法已成功应用于土壤样品分析。
