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Instrumentation and kinetic studies of surface-induced dissociation in a time-of-flight mass spectrometer.

机译：飞行时间质谱仪中表面诱导解离的仪器和动力学研究。

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摘要

The surface-induced dissociation (SID) method is introduced into a Bruker matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI TOF MS) as an efficient ion fragmentation method. Ion trajectory calculations using the SIMION 7.0 ion optics program are performed and results are combined with simple unimolecular decay calculations in order to study the kinetics of the SID processes. In this instrument, the observation time frame for SID fragments lies in the submicrosecond region, allowing the specific detection of submicrosecond fragmentation channels. MALDI-produced protonated peptides in the mass range of 700--1500 Da and radical ions produced by laser irradiation of fullerenes C60 and C70 are fragmented at a gold surface coated with a self-assembled monolayer of alkanethiol to obtain TOF SID TOF mass spectra. For the SID of peptides in the hyperthermal energy regime, a fragmentation time frame of tens to a few hundreds of nanoseconds was calculated for the observed fast fragmentation channels (Chapters 3 and 4). Theoretical and experimental peak shape comparisons assuming unimolecular decay kinetics indicated a log rate constant in the range 6--7 (Chapter 4). Energy and mass resolved kinetic studies are also carried out. The contribution of special structural features to peptide fragmentation and the possibility of different fragmentation mechanisms such as sequential and parallel pathways are investigated. The results indicate a unimolecular decay process for observed fast peptide fragments ruling out a surface-shattering mechanism. Fullerene ions, especially C60+., showed a fragmentation behavior producing C2n+. fragments with an even number of C units at collision energies in the range of 100--400 eV (Chapter 5). At around 400 eV, additional small fragments appeared that are apart by only a single C unit. According to the calculated fragmentation times and the theoretical and experimental peak shape comparisons assuming unimolecular decay kinetics, both these processes may be approximated by parallel fast unimolecular decay processes with fragmentation time frames of tens to hundreds of nanoseconds, although the poor theoretical and experimental peak shape matching for example in the decay of C60+. to C19+. may suggest deviations from a one-step unimolecular decay process.
机译：作为一种有效的离子碎裂方法，将表面诱导解离（SID）方法引入了布鲁克矩阵辅助的激光解吸/电离飞行时间质谱仪（MALDI TOF MS）中。使用SIMION 7.0离子光学程序进行离子轨迹计算，并将结果与​​简单的单分子衰减计算相结合，以研究SID过程的动力学。在此仪器中，SID片段的观察时间范围位于亚微秒范围内，从而可以专门检测亚微秒片段通道。 MALDI产生的质量范围为700--1500 Da的质子化肽和通过激光辐照富勒烯C60和C70产生的自由基离子在涂有链烷硫醇自组装单层的金表面断裂，以获得TOF SID TOF质谱图。对于处于高温能状态下的肽的SID，对于观察到的快速片段化通道，计算了数十至数百纳秒的片段化时间范围（第3章和第4章）。假设单分子衰减动力学的理论和实验峰形比较表明，对数速率常数在6--7范围内（第4章）。还进行了能量和质量分辨动力学研究。研究了特殊结构特征对肽片段化的贡献以及不同片段化机制（如顺序和平行途径）的可能性。结果表明观察到的快速肽片段的单分子衰变过程排除了表面破碎机理。富勒烯离子，特别是C60 +，表现出断裂行为，产生C2n +。在100--400 eV范围内的碰撞能量下具有偶数个C单位的碎片（第5章）。在大约400 eV处，出现了仅由一个C单元隔开的其他小片段。根据计算的碎裂时间以及假设单分子衰减动力学的理论和实验峰形比较，尽管理论和实验峰形较差，但可以通过并行快速的单分子衰减过程来近似这两个过程，其碎裂时间范围为数十至数百纳秒。例如在C60 +的衰减中匹配。到C19 +。可能暗示与单步衰变过程的偏离。

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  • 作者

    Majuwana Gamage, Chaminda.;

  • 作者单位

    The University of Arizona.;

  • 授予单位 The University of Arizona.;
  • 学科 Chemistry Analytical.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 221 p.
  • 总页数 221
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 化学;
  • 关键词

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