Development of a Novel Mass Spectrometric ... - Jacobs University

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Introduction spectrometry (FD-MS). 61 Combination of FI to GC and TOF HRMS (High resolution mass spectrometry) generated intact molecular ions [M] +• for both saturated and aromatic petroleum molecules. 62 Another study performed by Hsu et al. using this time LC/FI-MS, produced as well molecular ions for investigated paraffins and napthenes but fragment ions for isoparaffins like squalane. 63 FD-MS was employed to analyse large multiply branched saturated hydrocarbons, fragment ions were produced reflecting dehydrogenation, alkyl losses and alkene losses. 64 Field desorption ionisation however can also produce ions from nonpolar species but with less convenience at atmospheric pressure. 65,66 1.3.4 APPI APCI and APPI are known to produce intact ions for polar hydrocarbons as [M- H]ˉ, [M+H] + or [M] •+ but for saturated hydrocarbons the techniques have proven limited. 67,68 APPI is also used to analyze fairly nonpolar molecules. The illumination of the sample molecules by vacuum ultraviolet lamp produces radical molecular ions by photoionisation. For example PAH were produced as protonated upon APPI, but APPI can’t be used to ionise saturated paraffins. APPI, however, was found to produce at the same time protonated, deprotonated and molecular ion radicals of nonpolar aromatic compounds like polyaromatic sulfur heterocycles (PASH). 30 This leads to complication in composition assignment of these compounds in petroleum fractions. It was as well shown that the ionisation efficiency of the parent radical ion is enhanced once a dopant is added. The APPI ionisation technique becomes dopant-assisted (DA-APPI). For example toluene works by enhancing proton transfer and charge exchange reactions. Simultaneous production of protonated and radical molecular ions is observed. Overall APPI is thought to possess a potential to cover a broader range of compounds of crude oil. Particularly APPI was demonstrated to analyse asphaltene producing good results. 69 13
Introduction 1.3.5 APLI Other crude oil ionisation methods included atmospheric pressure laser ionisation (APLI). This technique was introduced by Benter and colleagues. 70-73 Since APLI is found sensitive for aromatic compounds, it is considered capable to reduce complexity of crude oil. Shrader et al. demonstrated coupling of APLI with FT- ICR MS as a suitable approach for the analysis of aromatic species in complex crude oil fractions. 74 A more recent paper also investigated the potential of APLI to complement the ionisation process of crude oil analytes compared to other ionisation techniques like ESI and APPI. Results showed preference of APLI over the other techniques in the analysis of crude oil fraction. 75 1.3.6 APCI, LIAD/CI and LIAD/APCI Another more generally applicable ionisation technique is the atmospheric pressure chemical ionisation (APCI). Introduced by Horning in 1970, APCI produced a wide variety of different types of ions from a given analyte. An LC-APCI-MS was used to identify classes of PAHs in mussels. A proton transfer ion (M+H) + and a charge transfer radical ion (M) •+ were observed for the studied PAHs using different mobile phases. 27 The latter ionisation patterns are produced simultaneously in typical APCI processes. APCI has as well been used for petroleomic analyses 62,76,77 where it was considered limited due to its low sensitivity. Nevertheless, APCI, a popular ionization technique, has been considerably used for detection of n-alkanes. 78-81 Alkanes are known to be used as probes for APCI-MS ionization processes. Karasek et al. analysed n-alkyl halides 82 and n-alkanes (C 5 H 12 -C 15 H 32 ). 83 For alkyl halides (MX), (M-1) + ions were formed by hydrogen abstraction, while for n- alkanes, formation of (MH) + and (MNO) + adduct ions was postulated. Bell et al. 78 investigated some n-alkanes in 1994. He found that n-alkanes were characterised by composites of protonated and monohydrated species (M-H) + , (M-3H) + and (M- 3H) + H 2 O. These ions were generated by corona discharge and monitored by ion mobility. A hydrogen abstraction was supposed for the formation of the above 14
Page 1 and 2: Development of a Novel Mass Spectro
Page 3 and 4: Declaration of Authorship I ,Nadim
Page 5 and 6: This work has been carried out unde
Page 7 and 8: Contents Contents Declaration of Au
Page 9 and 10: List of Figures List of Figures Fig
Page 11 and 12: List of Figures Figure 3-39 MS 2 fr
Page 13 and 14: List of Tables List of Tables Table
Page 15 and 16: Abbreviations Abbreviations APCI AP
Page 17 and 18: Abbreviations UV VGOs VOCs VRs ultr
Page 19 and 20: Introduction Analytical chemistry h
Page 21 and 22: Introduction 1.2 Presence and Fate
Page 23 and 24: Introduction aliphatic hydrocarbons
Page 25 and 26: Introduction Figure 1-1 Examples of
Page 27 and 28: Introduction Figure 1-2 Range of io
Page 29: Introduction fractions. 42 Another
Page 33 and 34: Introduction products). Other molec
Page 35 and 36: Introduction Other studies performe
Page 37 and 38: Introduction APLI-FT ICR-MS Crude o
Page 39 and 40: Introduction spectrometry in as muc
Page 41 and 42: Introduction catalytic processing t
Page 43 and 44: Introduction Figure 1-6 Kendrick ma
Page 45 and 46: Introduction including determinatio
Page 47 and 48: Introduction 1.5 Scope and Signific
Page 49 and 50: Experimental e) Other model mixture
Page 51 and 52: Experimental 2.2.2 Preparation of O
Page 53 and 54: Experimental 2.4 Graphical Presenta
Page 55 and 56: Results and Discussion experiment.
Page 57 and 58: Results and Discussion Intens. [%]
Page 59 and 60: Results and Discussion common featu
Page 61 and 62: Results and Discussion 3.2 APCI-TOF
Page 63 and 64: Results and Discussion These compou
Page 67 and 68: Results and Discussion Ions were pr
Page 71 and 72: Results and Discussion procedure ba
Page 75 and 76: Results and Discussion to produce m
Page 77 and 78: Results and Discussion 519.5863 519
Page 79 and 80: Results and Discussion Higher mass
Page 81 and 82:
Results and Discussion Intens. [%]
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
Results and Discussion isolated fro
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Page 91 and 92:
Page 93 and 94:
Results and Discussion 3.4.5 Tandem
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Results and Discussion injected int
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Page 101 and 102:
Results and Discussion 3.4.8 Quanti
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Results and Discussion Int. x 10000
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Results and Discussion Table 3.6 Qu
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Results and Discussion assessment o
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Results and Discussion hydrocarbons
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Page 115 and 116:
Page 117 and 118:
Results and Discussion of n-alkanes
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Results and Discussion flow (in I2)
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Results and Discussion Other intere
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Results and Discussion Figure 3-80
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Results and Discussion KMD 2.4 2.2
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Results and Discussion KMD 1.1 1 Le
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Results and Discussion 3.6.4 Asphal
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Conclusions In conclusion we could
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References References 1. Fay, R. M.
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References 23. Colavecchia, M. V.,
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References 47. Dzidic, I., Petersen
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References Hydroconversion Processe
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References 91. Golovlev, V. V., All
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Appendix Light shredder waste Meas.
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419.4592 C 30 H 59 419.4611 4.6 421
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Liqui Moly car motor oil Meas. m/z
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345.3511 C 25 H 45 345.3516 1.5 349
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