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首页> 外文期刊>Magnetic Resonance in Chemistry: MRC >Nontarget analysis of Murchison soluble organic matter by high-field NMR spectroscopy and FTICR mass spectrometry
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Nontarget analysis of Murchison soluble organic matter by high-field NMR spectroscopy and FTICR mass spectrometry

机译：高场NMR光谱和FTICR质谱法对Murchison可溶性有机物的非目标分析

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High-field NMR spectra of Murchison meteorite methanolic extracts revealed primarily aliphatic extraterrestrial organic matter (EOM) with near statistical branching of commonly C3-5 units separated by heteroatoms and aromatic units. The ratios of CCH, OCH and C-sp2H units were 89:8:3, whereas carbon-based aliphatic chain termination was in the order methyl >COOH>CH(CH3)COOH. Aliphatic methine carbon was abundant, but its weak NMR signatures were primarily deduced from JRES (J-resolved) NMR spectra. Carbon NMR spectra were dominated by methylene and methyl carbon; strong apodization revealed methine carbon, of which about 20% was aromatic. Extrapolation provided 5-7% aromatic carbon present in Murchison soluble EOM. Compositional heterogeneity in Murchison methanolic extracts was visible in NMR and Fourier transform ion cyclotron (FTICR) mass spectra obtained from a few cubic millimeters of solid Murchison meteorite; increasing sample size enhanced uniformity of NMR spectra. Intrinsic chemical diversity and pH-dependent chemical shift variance contributed to the disparity of NMR spectra. FTICR mass spectra provided distinct clustering of CHO/CHOS and CHNO/CHNOS molecular series and confirmed the prevalence of aliphatic/alicyclic (73%) over single aromatic (21%) and polyaromatic (6%) molecular compositions, suggesting extensive aliphatic substitution of aromatic units as proposed by NMR. Murchison soluble EOM molecules feature a center with enhanced aromatic and heteroatom content, which provides rather diffuse and weak NMR signatures resulting from a huge overall chemical diversity. The periphery of Murchison EOM molecules comprises flexible branched aliphatic chains and aliphatic carboxylic acids. These project on narrow ranges of chemical shift, facilitating observation in one-dimensional and two-dimensional NMR spectra. The conformational entropy provided by these flexible surface moieties facilitates the solubility of EOM. Copyright (c) 2015 John Wiley & Sons, Ltd.
机译：Murchison陨石甲醇提取物的高场NMR光谱显示主要是脂肪族的地球外有机物（EOM），通常由杂原子和芳香族单元分隔的C3-5单元具有接近统计的分支。 CC H ，OC H 和C的比率-sp2 H 单元为89：8：3，而基于碳的脂族链终止顺序为甲基> COOH> CH（CH3）哦脂肪族次甲基碳很丰富，但是其弱的NMR特征主要是从JRES（J分辨）NMR光谱推导出的。碳核磁共振谱以亚甲基和甲基碳为主;强烈的切趾显示次甲基碳，其中约20％为芳烃。外推提供了Murchison可溶EOM中存在的5-7％芳族碳。默奇森甲醇提取物中的成分异质性在NMR和傅立叶变换离子回旋加速器（FTICR）质谱图中可见，该质谱图是从几立方毫米的固态默奇森陨石获得的。增加样品量可增强NMR光谱的均匀性。内在的化学多样性和pH依赖的化学位移差异导致了NMR谱图的差异。 FTICR质谱图提供了CHO / CHOS和CHNO / CHNOS分子系列的独特聚类，并证实了脂族/脂环族（73％）高于单一芳族化合物（21％）和多芳族化合物（6％）分子组成，表明芳族化合物广泛地被脂族取代由NMR提出的单元。 Murchison可溶性EOM分子的中心具有增强的芳族和杂原子含量，由于巨大的整体化学多样性，该中心提供了相当分散且较弱的NMR特征。 Murchison EOM分子的外围包含柔性支链脂族链和脂族羧酸。这些投影在狭窄的化学位移范围内，有利于在一维和二维NMR光谱中的观察。这些柔性表面部分提供的构象熵促进了EOM的溶解性。版权所有（c）2015 John Wiley＆Sons，Ltd.

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