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

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Results and Discussion Intens. [%] 100 80 60 40 20 393.3 394.3 395.4 396.4 397.4 398.4 399.4 400.4 401.4 405.3 403.4 402.4 404.4 406.4 407.4 408.4 409.4 410.4 411.4 412.4 413.4 +MS 414.4 0 392.5 395.0 397.5 400.0 402.5 405.0 407.5 410.0 412.5 m/z Figure 3-23 Enlarged section of (+) MS showing bimodal distribution of odd and even mass ions The latter interpreted ionisation behavior of hydrocarbon ions in solid waste was anticipated from our previous results of ionisation behavior of n-alkanes and other hydrocarbon model standards upon APCI. These model standards produced also stable (M-1) + ions with neighboring molecular ions M •+ without any fragmentation under similar APCI conditions. This indicated that the stable ions appearing in the positive mass spectrum (+MS) are intact ions expressing their hydrocarbons that exist in the waste sample. 3.4.2 Calibration After this fundamental description of the explored chemical content of the waste, a molecular formula assignment was required for all compounds present in the waste spectrum. However before identifying n-alkanes ,that are expected to be found within the waste chemical content, the obvious obstacle was to find suitable calibrant for the APCI-MS high resolution mass measurements. The generally used commercial APCI/APPI acetonitrile calibrant was not really effective towards a low-mass error assignment of waste sample components of n-alkanes and others. This is due to the fact that the calibrant’s range, shown in figure 3-24, did not fully cover the alkane mass range of interest (m/z 200-600) in these experiments. To overcome this problem, I have employed the C7-C40 n-alkane standard (figure 3- 25) mixture to be used for m/z calibration using an enhanced quadratic calibration 57
Results and Discussion to produce mass errors around 3 ppm. An enhanced quadratic fit provides the best relative standard deviation (RSD) around 1 of the analytes of the calibrant compared to linear or quadratic fits. For the calibration curve all (M-1) + ions of n- alkanes were used as reference masses, serving as an external calibrant for the waste analysis. The speciation of most of the components including n-alkanes within the waste sample was made possible by this intriguing employment of the C7-C40 calibrant standard. The combination of the calibration method establishment with the preceded thorough understanding of the ionisation of hydrocarbons provided a rational elemental assignment of the molecular composition of the waste complex mixture. Table 3.3 shows the molecular formula list of n-alkanes obtained from a shredder waste sample under investigation. Intens. [%] 100 80 622.0 922.0 +MS 60 40 20 322.0 1522.0 0 663.4 850.0 200 400 600 800 1000 1200 1400 m/z Figure 3-24 APCI/APPI standard recommended calibrant for APCI source With this result we could tentatively identify all n-alkanes (C13-C40) by their apparent (M-1) + representative ions in a real life complex waste sample displaying a UCM hump in a gas chromatogram. However the identified series of n-alkanes is only a significant part of the chemical content of the waste. The determination of the other components within the waste spectrum will lead to clarify the chemical content of the unresolved complex mixture. 58
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Development of a Novel Mass Spectro
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Declaration of Authorship I ,Nadim
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This work has been carried out unde
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Contents Contents Declaration of Au
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List of Figures List of Figures Fig
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List of Figures Figure 3-39 MS 2 fr
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List of Tables List of Tables Table
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Abbreviations Abbreviations APCI AP
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Abbreviations UV VGOs VOCs VRs ultr
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Introduction Analytical chemistry h
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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 and 30: Introduction fractions. 42 Another
Page 31 and 32: Introduction 1.3.5 APLI Other crude
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 73: Results and Discussion Intens. [%]
Page 77 and 78: Results and Discussion 519.5863 519
Page 79 and 80: Results and Discussion Higher mass
Page 87 and 88: Results and Discussion isolated fro
Page 93 and 94: Results and Discussion 3.4.5 Tandem
Page 97 and 98: Results and Discussion injected int
Page 101 and 102: Results and Discussion 3.4.8 Quanti
Page 103 and 104: Results and Discussion Int. x 10000
Page 105 and 106: Results and Discussion Table 3.6 Qu
Page 107 and 108: Results and Discussion assessment o
Page 109 and 110: Results and Discussion hydrocarbons
Page 117 and 118: Results and Discussion of n-alkanes
Page 119 and 120: Results and Discussion flow (in I2)
Page 121 and 122: Results and Discussion Other intere
Page 123 and 124: 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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