Online Counter Gradient LC-FT-ICR-MS Enables Detection of Highly Polar Natural Organic Matter Fractions
Online Counter Gradient LC-FT-ICR-MS Enables Detection of Highly Polar Natural Organic Matter Fractions
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DOI：
10.1021/acs.analchem.0c04426
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发表时间：
2021-01-26
影响因子：
7.4
通讯作者：
Lechtenfeld, Oliver J.
中科院分区：
文献类型：
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作者：
Han, Limei;Kaesler, Jan;Lechtenfeld, Oliver J.
天然有机物（NOM）是天然有机分子的高度复杂混合物。 NOM 分子表征方法的最新发展表明，ESIFT-ICR 与液相色谱 (LC) 联用是一种很有前景的方法，可以获取有关 NOM 分子的化学信息（例如极性和分子大小）。然而，由于 LC-FT-ICR-MS 梯度洗脱过程中溶剂组成发生变化，电离条件在整个色谱分离过程中也会发生变化。在本研究中，我们应用了 LC 柱后反梯度 (CG)，以确保瞬态 ESI-MS 信号的溶剂条件稳定。 Suwanee 河黄腐酸 (SRFA) 标准品和泥炭孔隙水被用作代表性溶解 NOM 样品，用于方法开发和验证。我们的结果表明，与直接输注 (DI) 相比，CG-LC 模式下的极性 NOM 级分（用 0.6 洗脱）大 20 倍以上（5715 与 266 MF）。我们得出的结论是，在 NOM 的 LC-FT-ICR-MS 分析中应用柱后反梯度提供了对 NOM 极性最强组分的新颖见解，而这在传统 DI 测量中是无法获得的。
Natural organic matter (NOM) is a highly complex mixture of natural organic molecules. The recent developments in NOM molecular characterization methods have shown that ESIFT-ICR hyphenated with liquid chromatography (LC) is a promising approach to also obtain chemical information (such as polarity and molecular size) about NOM molecules. However, due to changing solvent composition during gradient elution in LC-FT-ICR-MS, ionization conditions also change throughout the chromatographic separation process. In this study, we applied a post-LC column counter gradient (CG) to ensure stable solvent conditions for transient ESI-MS signals. Suwanee River Fulvic Acid (SRFA) standard and a peat pore water were used as representative dissolved NOM samples for method development and validation. Our results show that in polar NOM fractions (which elute with 0.6) were more than 20 times larger for CG-LC mode as compared to direct infusion (DI) (5715 vs 266 MF). We conclude that the application of a postcolumn counter gradient in LC-FT-ICR-MS analyses of NOM offers novel insight into the most polar fractions of NOM which are inaccessible in conventional DI measurements.