Development of Alditol Acetate Derivatives for the Determination of 15N-Enriched Amino Sugars by Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry.
Development of Alditol Acetate Derivatives for the Determination of 15N-Enriched Amino Sugars by Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry.
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DOI：
10.1021/acs.analchem.8b04838
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发表时间：
2019-03
影响因子：
7.4
通讯作者：
M. Reay;T. Knowles;Davey L. Jones;R. Evershed
中科院分区：
文献类型：
--
作者：
M. Reay;T. Knowles;Davey L. Jones;R. Evershed
氨基糖可作为评价土壤微生物在土壤活性氮循环中作用的指标。本文详细介绍了气相色谱-燃烧-同位素比质谱法（GC-C-IRMS）的适用性的评估，用于分析15 N-富集的氨基糖作为糖醇乙酸酯衍生物之前，应用一种新的15 N稳定同位素探测（SIP）的方法，以氨基糖。用于GC的糖醇乙酸酯衍生物的有效衍生化和净化使用市售氨基糖（包括葡糖胺、甘露糖胺、半乳糖胺和胞壁酸）作为实验室标准品来实现。VF-23 ms固定相被发现产生所有四种化合物的最佳分离。糖醇乙酸酯衍生物的结构使用气相色谱/质谱（GC/MS）确认。对于GC-C-IRMS测定，两点归一化的实施证实了最佳载气流速为1.7 mL min-1。当柱上进样30 nmol N时，δ 15 N值测定的线性高达δ 15 Nt为469 ± 3.1‰（其中δ 15 Nt为独立测量的δ 15 N值），低样品量下偏离δ 15 Nt的方向取决于分析物的15 N丰度。当运行高度富集的标准品（469 ± 3.1‰）时，观察到的运行间和运行内记忆效应显著（P < 0.007）;因此，必须考虑分析运行顺序和同一样品中分析物15 N富集的变化。研究参数证实了氨基糖的糖醇乙酸酯衍生物在富集范围（天然丰度至469 ± 3.1‰）内的线性（柱上分析物量超过30 nmol N）方面用于15 N富集氨基糖的GC-C-IRMS分析的同位素耐用性。
Amino sugars can be used as indices to evaluate the role of soil microorganisms in active nitrogen (N) cycling in soil. This paper details the assessment of the suitability of gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) for the analysis of 15N-enriched amino sugars as alditol acetate derivatives prior to application of a novel 15N stable isotope probing (SIP) approach to amino sugars. The efficient derivatization and cleanup of alditol acetate derivatives for GC was achieved using commercially available amino sugars, including glucosamine, mannosamine, galactosamine, and muramic acid, as laboratory standards. A VF-23ms stationary phase was found to produce optimal separations of all four compounds. The structure of the alditol acetate derivatives was confirmed using gas chromatography/mass spectrometry (GC/MS). For GC-C-IRMS determinations, implementation of a two-point normalization confirmed the optimal carrier gas flow rate to be 1.7 mL min-1. Linearity of δ15N value determinations up to δ15Nt of 469 ± 3.1‰ (where δ15Nt is the independently measured δ15N value) was confirmed when 30 nmol N was injected on-column, with the direction of deviation from δ15Nt at low sample amount dependent on the 15N abundance of the analyte. Observed between- and within-run memory effects were significant ( P < 0.007) when a highly enriched standard (469 ± 3.1‰) was run; therefore, analytical run order and variation in 15N enrichment of analytes within the same sample must be considered. The investigated parameters have confirmed the isotopic robustness of alditol acetate derivatives of amino sugars for the GC-C-IRMS analysis of 15N-enriched amino sugars in terms of linearity over an enrichment range (natural abundance to 469 ± 3.1‰) with on-column analyte amount over 30 nmol N.