Speciation of Heteroatom Compounds in Complex Mixtures by In-source Atmospheric Pressure Ionization H/D-exchange Mass Spectrometry : In-source 대기압 이온화 H / D-exchange 질량 분석법에 의한 복합체에서의 헤테로 원자 화합물의 특성 분석

다국어 초록 (Multilingual Abstract)

This study explores the potential of the H/D-exchange atmospheric pressure ionization (API-HDX-MS) technique for its application to complex mixtures. Then the optimized API-HDX-MS method was employed for the structural determination of several diverse nitrogen-, oxygen- and sulfur-containing structures in crude oil samples. The evaluation of the HDX mass spectra obtained from nitrogen-, oxygen- and sulfur-containing compounds by atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) demonstrated that the extent of HDX of the ions was structure-dependent. HDX reaction mechanism was also investigated by combining APPI HDX experiments and theoretical calculations. It was suggested that the double steps reactions are favorable compared to single step reaction for HDX between sulfur compounds (thiols) and deuterated methanol. The results found from the structural characterization of nitrogen compounds in resins of shale oil analyzed by (+) APCI HDX MS suggested mainly pyridine type structures. The speciation of oxygen compounds in photo-degraded oil analyzed by (+)/(-)APPI HDX MS suggested mainly naphthalenedione type structures in positive mode and carboxylic acids containing aldehyde, ketone or ester groups in negative mode. In speciation of sulfur compounds in fractionated oil, HDX of thiol was found for the first time using (+) APPI HDX and suggested mainly cyclic dithiols type structures. Finally, a continuous in-source APPI HDX MS method was developed to overcome the solubility problem of analytes in the current HDX-MS approaches where deuterated solvents were premixed with sample solutions before ionization. The method was validated by distinguishing the number of labile hydrogens in diverse nitrogen-, oxygen-, and sulfur containing compounds, as well as in the polar fraction of crude oil. Thus APCI/APPI HDX MS can be added to previously reported chemical ionization, electrospray ionization-based HDX methods, which can be used for structural elucidation of complex mixtures.

국문 초록 (Abstract)

이는 복합 혼합물에 적용하기 위한 H/D-exchange 대기압 이온화 (API-HDX-MS) 기술의 잠재력을 탐구하는 연구이다. 최적화된 API-HDX-MS 방법은 원유 시료 속에 있는 다양한 질소, 산소, 황을 포함하는 화합물들의 구조를 규명하는데 사용될 수 있다. 대기압 화학 이온화 (APCI) 및 대기압 광 이온화 (APPI)에 의해 질소 및 산소, 황을 포함하는 화합물로부터 얻은 HDX 질량 값들의 변화가 화합물의 구조에 의존적이라는 것을 입증했다. HDX의 반응 메커니즘 또한, APPI -HDX 실험과 이론적 계산을 결합하여 규명하였다. 이 결과 황 화합물 (티올)과 중수소 메탄올 사이의 HDX 반응이 두개의 스텝을 가지는 이중 단계 반응으로 진행됨이 보여졌다. APCI HDX MS로 분석한 셰일 오일 추출물 샘플에서 질소 화합물들이 피리딘 형태의 구조를 가지고 있음을 제시했다. (+)/(-) APPI HDX MS로 분석한 광분해 오일의 스펙트럼을 해석함으로써 산화된 오일에 알데히드, 케톤 또는 카르복실산 구조를 가지는 화합물들이 존재함을 제안하였다. 분별된 원유 속에 포함된 황화합물을 (+) APPI HDX를 사용하여 연구하여 티올의 HDX를 처음으로 보고 하였고 또한 이 화합물들이 순환 티올 형태의 구조를 가짐을 제안하였다. 마지막으로 중수소화된 용매를 이온화 전에 샘플 용액과 미리 혼합한 경우 발생하는 분석물의 용해도 문제를 극복하기 위해 연속적인 내부 소스 APPI HDX MS 방법이 개발되었다. 이 방법을 이용하여 다양한 질소 및 산소, 황을 포함하는 화합물과 원유의 극성 부분에서 치환이 가능한 수소의 수를 구별함으로써 검증되었다. 따라서 APCI/APPI HDX MS는 이전에 보고된 화학 이온화, 전자 혼합물 이온화 기반 HDX 방법에 추가 될 수 있으며, 복잡한 혼합물의 구조적 해명에 사용될 수 있다.

목차 (Table of Contents)

• Chapter 1 : Introduction 1
• 1.1 Introduction 2
• 1.2 Methods for Structural analysis 3
• 1.3 Development of Hydrogen/Deuterium Exchange-Mass Spectrometry (HDX-MS) 4
• 1.4 Research Outline 5
• 1.5 References 8
• Chapter 2 : Theory and Methodology 11
• 2.1 Hydrogen-Deuterium Exchange (HDX) 12
• 2.2 Coupling of HDX-MS 12
• 2.2.1 In-solution HDX 13
• 2.2.2 HDX under vaccum 13
• 2.2.3 In-source HDX 15
• 2.2.3.1 Atmospheric Pressure Chemical Ionization (APCI) HDX-MS 15
• 2.2.3.2 Atmospheric Pressure Photoionization (APPI) HDX-MS 16
• 2.3 Mass Analyzers 16
• 2.3.1 Quadrupole-ion trap 17
• 2.3.2 Fourier transform ion cyclotron resonance mass spectrometer 18
• 2.4 Methodology 19
• 2.4.1 Preparation of Standards 19
• 2.4.2 Preparation of Samples 19
• 2.4.3 HDX-MS Experiment 19
• 2.4.4 MS Conditions 20
• 2.4.5 Data Analysis 21
• 2.4.6 Notation for Exchanged Peaks 21
• 2.5 HDX-MS Optimization 22
• 2.6 References 23
• Chapter 3 : H/D-Exchange Mechanism 25
• 3.1 Introduction 26
• 3.2 Experimental Section 28
• 3.3 Computational Details 28
• 3.4 Results and Discussion 30
• 3.4.1 MS Results 30
• 3.4.2 Proposed HDX mechanism 32
• 3.5 Conclusion 34
• 3.6 References 35
• Chapter 4 : Speciation of Nitrogen- Compounds in Crude Oil by APCI HDX MS 38
• 4.1 Introduction 39
• 4.2 Experimental Section 41
• 4.2.1 SARA Fractionation of Shale Oil 41
• 4.2.2 HDX-MS experiments 42
• 4.3 Results and Discussion 44
• 4.3.1 Optimization of HDX-MS conditions 44
• 4.3.2 Analysis of nitrogen-standards 49
• 4.3.3 Application of (+) APCI HDX-MS 53
• 4.4 Conclusions 55
• 4.5 References 56
• Chapter 5 : Speciation of Oxygen- Compounds in Crude oil by APCI and APPI HDX MS 60
• 5.1 Introduction 61
• 5.2 Experimental Section 62
• 5.2.1 Photo-oxidation of Oil Sample 62
• 5.2.2 HDX MS experiments 62
• 5.3 Results and Discussion 63
• 5.3.1 Optimization of HDX MS conditions 63
• 5.3.2 Analyses of oxygen standards 67
• 5.3.3 Application to crude oil by (+) APPI HDX MS 80
• 5.3.4 Application to crude oil by () APPI HDX MS 81
• 5.4 Conclusions 82
• 5.5 References 83
• Chapter 6 : Speciation of Sulfur- Compounds in Crude Oil by APPI HDX-MS 87
• 6.1 Introduction 88
• 6.2 Experimental Section 89
• 6.2.1 Separation of crude oil 89
• 6.2.2 HDX-MS experiment 90
• 6.3 Results and Discussion 92
• 6.3.1 Optimization of HDX MS conditions 92
• 6.3.2 Analysis of sulfur standards 96
• 6.3.3 Application to crude oil 100
• 6.4 Conclusion 104
• 6.5 References 105
• Chapter 7 : In-Source APPI HDX MS with Continuous Feeding of D2O 109
• 7.1 Introduction 110
• 7.2 Experimental Section 111
• 7.2.1 Deuterating solvent 111
• 7.2.2 Fractionation of Oil Sample 114
• 7.2.3 Proposed design 114
• 7.3 Results and Discussion 115
• 7.3.1 Method validation 115
• 7.3.2 Application to Standard Compounds 122
• 7.3.3 Application to crude oil 124
• 7.4 Conclusions 125
• 7.5 References 126
• Chapter 8 : Executive summary and conclusion 129
• 8.1 Executive summary and conclusion 130
• Acknowledgments 132
• Abstract 134
• 초록 135