Unlocking PAH Ionization in Negative-Mode ESI Orbitrap MS Using Tetramethylammonium Hydroxide: A Petroleomic Strategy

IF 2.7 2区 化学 Q2 BIOCHEMICAL RESEARCH METHODS
Deborah V. A. de Aguiar, , , Lidya C. da Silva*, , , Iris M. Júnior, , , Alexandre de O. Gomes, , and , Boniek Gontijo*, 
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引用次数: 0

Abstract

The selective ionization of cyclopentadiene-derived polycyclic aromatic hydrocarbons (PAHs) in complex matrices remains a persistent challenge in direct ionization mass spectrometry, particularly under atmospheric pressure ionization (API) conditions. In this study, tetramethylammonium hydroxide (TMAH) was evaluated as a solvent modifier to enhance the ionization efficiency of PAHs in negative-ion mode using high-resolution Orbitrap MS. A systematic assessment with equimolar mixtures of neutral and acidic model compounds was performed to elucidate the fundamental effects of TMAH on ion suppression, deprotonation mechanisms, and gas-phase ion chemistry. The incorporation of TMAH significantly improved the detection of weakly acidic and neutral PAHs by promoting efficient gas-phase deprotonation, thus overcoming conventional ESI limitations. To demonstrate the method’s analytical robustness, TMAH-assisted ESI was subsequently applied to crude oil samples, enabling the detection of hydrocarbon species otherwise inaccessible under standard conditions, with a particular focus on low-alkylated fluorene derivatives. These results establish a simple and effective strategy for expanding the analytical scope of ESI-MS toward nonpolar and weakly acidic hydrocarbons, offering a valuable tool for the advanced molecular characterization of complex organic mixtures.

使用四甲基氢氧化铵在负模式ESI轨道阱质谱中解锁多环芳烃电离:一种石油策略。
环戊二烯衍生的多环芳烃(PAHs)在复杂基质中的选择性电离仍然是直接电离质谱法的一个持续挑战,特别是在大气压电离(API)条件下。在本研究中,利用高分辨率的Orbitrap质谱仪对四甲基氢氧化铵(TMAH)作为溶剂改性剂在负离子模式下提高多环芳烃的电离效率进行了评价,并通过中性和酸性模型化合物的等摩尔混合物进行了系统评价,以阐明TMAH对离子抑制、去质子化机制和气相离子化学的基本影响。TMAH的掺入通过促进高效气相去质子化,显著提高了弱酸性和中性多环芳烃的检测,从而克服了传统ESI的局限性。为了证明该方法的分析稳健性,随后将tmah辅助ESI应用于原油样品,从而能够检测在标准条件下无法检测到的碳氢化合物种类,特别是低烷基化芴衍生物。这些结果为扩大ESI-MS对非极性和弱酸性碳氢化合物的分析范围建立了一种简单有效的策略,为复杂有机混合物的高级分子表征提供了有价值的工具。
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来源期刊
CiteScore
5.50
自引率
9.40%
发文量
257
审稿时长
1 months
期刊介绍: The Journal of the American Society for Mass Spectrometry presents research papers covering all aspects of mass spectrometry, incorporating coverage of fields of scientific inquiry in which mass spectrometry can play a role. Comprehensive in scope, the journal publishes papers on both fundamentals and applications of mass spectrometry. Fundamental subjects include instrumentation principles, design, and demonstration, structures and chemical properties of gas-phase ions, studies of thermodynamic properties, ion spectroscopy, chemical kinetics, mechanisms of ionization, theories of ion fragmentation, cluster ions, and potential energy surfaces. In addition to full papers, the journal offers Communications, Application Notes, and Accounts and Perspectives
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