Elucidating molecular structures of nonalkylated and short-chain alkyl (n < 5, (CH₂)n) aromatic compounds in crude oils by a combination of ion mobility and ultrahigh-resolution mass spectrometries and theoretical collisional cross-section calculations.
Elucidating molecular structures of nonalkylated and short-chain alkyl (n < 5, (CH₂)n) aromatic compounds in crude oils by a combination of ion mobility and ultrahigh-resolution mass spectrometries and theoretical collisional cross-section calculations.
复制标题
通过结合离子淌度、超高分辨率质谱和理论碰撞截面计算，阐明原油中非烷基化和短链烷基（n < 5，(CH2)n）芳香族化合物的分子结构。
作者：
Arif Ahmed;Yunju Cho;K. Giles;Eleanor Riches;Jong Wha Lee;Hugh Inkon Kim;C. Choi;Sunghwan Kim
超高分辨率质谱法已经允许确定构成原油的化合物的元素式。然而，阐明分子结构仍然是一个分析挑战。在此，我们提出并演示了一种结合离子迁移率质谱（IM-MS）、超高分辨率质谱和理论碰撞截面（CCS）计算的方法来确定原油中发现的芳香族化合物的分子结构。该方法由三个步骤组成。首先，根据超高分辨率质谱确定的元素式建议化学结构。其次，理论CCS值计算基于这些建议的结构。第三，将所提出的结构的计算的CCS值与来自IM-MS数据的实验确定的CCS值进行比较，以提供所提出的结构。为了验证概念，分析了原油中常见的31种非烷基化和短链烷基（n < 5，（CH 2）n）芳香族化合物。理论和实验CCS值在5% RMS误差内匹配。然后使用这种方法提出原油样品中选定m/z区域的化合物结构。总体而言，离子迁移质谱，超高分辨率质谱和理论计算的组合被证明是一个有用的工具，用于阐明复杂混合物中化合物的化学结构。
Ultrahigh-resolution mass spectrometry has allowed the determination of elemental formulas of the compounds comprising crude oils. However, elucidating molecular structures remains an analytical challenge. Herein, we propose and demonstrate an approach combining ion mobility mass spectrometry (IM-MS), ultrahigh-resolution mass spectrometry, and theoretical collisional cross-section (CCS) calculations to determine the molecular structures of aromatic compounds found in crude oils. The approach is composed of three steps. First, chemical structures are suggested based on the elemental formulas determined from ultrahigh-resolution mass spectra. Second, theoretical CCS values are calculated based on these proposed structures. Third, the calculated CCS values of the proposed structures are compared with experimentally determined CCS values from IM-MS data to provide proposed structures. For proof of concept, 31 nonalkylated and short-chain alkyl (n < 5, (CH2)n) aromatic compounds commonly observed in crude oils were analyzed. Theoretical and experimental CCS values matched within a 5% RMS error. This approach was then used to propose structures of compounds in selected m/z regions of crude oil samples. Overall, the combination of ion mobility mass spectrometry, ultrahigh-resolution mass spectrometry, and theoretical calculations was shown to be a useful tool for elucidating chemical structures of compounds in complex mixtures.