Natural organic matter (NOM) plays an important role in elemental cycles and ecology. Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) is an ultrahigh resolution technique used to molecularly resolve the complexity of NOM mixtures. However, even the very high mass resolution of FT-ICR-MS may result in multiple formula assignments to peaks in an NOM spectrum, especially at the high mass-to-charge ratio (m/z). The absorption mode is one option to process raw FT-ICR-MS data that can further increase the resolution of the peaks and has not been widely applied in NOM studies. In this study, we show the advantages of using the absorption mode for the analysis of NOM samples using a reference sample (Suwannee River fulvic acid). The absorption mode increased the precision of peak detection as well as the number (+23%) and accuracy of formula assignment (by 28%) when compared to the magnitude mode, besides achieving three times higher resolution. The results presented here highlight the potential to reduce the error threshold used during molecular formula assignment. In conclusion, the absorption mode shows advantages in the processing of NOM samples and other complex mixtures and should be promoted in the NOM community.

中文翻译：

---

吸收模式光谱处理通过傅里叶变换离子回旋共振质谱提高天然有机物分析的数据质量。

天然有机物 (NOM) 在元素循环和生态学中起着重要作用。傅里叶变换离子回旋共振质谱 (FT-ICR-MS) 是一种超高分辨率技术，用于分子解析 NOM 混合物的复杂性。然而，即使 FT-ICR-MS 的质量分辨率非常高，也可能导致 NOM 光谱中峰的多个分子式分配，尤其是在高质荷比 (m/z) 下。吸收模式是处理原始 FT-ICR-MS 数据的一种选择，可以进一步提高峰的分辨率，但尚未广泛应用于 NOM 研究。在本研究中，我们展示了使用参考样品（Suwannee 河富里酸）分析 NOM 样品的吸收模式的优势。与幅度模式相比，吸收模式提高了峰检测的精度以及公式分配的数量（+23%）和准确度（28%），并且分辨率提高了三倍。此处显示的结果强调了降低分子式分配过程中使用的错误阈值的潜力。总之，吸收模式在 NOM 样品和其他复杂混合物的处理中显示出优势，应在 NOM 社区中推广。