Fundamental Mass Spectrometry Measurements of Electrosprayed and Matrix-Assisted Laser Desorbed Ions Using an Improved Superconducting Tunnel Junction Detector

Mark E. Bier和他在卡内基梅隆大学的学生得到了NSF化学部化学测量和成像（CMI）计划的支持，以进行基础研究，目标是改进质谱检测器（MS，表征化学品和生物化学品的主要工具）。 数据和检测器技术的最新进展使得在MS分析期间检测离子时能够实现响应速度和能量分辨率的改进。 Bier小组正在研究离子撞击探测器时沉积的能量的测量是否与离子的结构有关-这是理解分子如何发挥作用的关键信息。 例如，这可以改善对大分子复合物（如病毒颗粒和合成纳米颗粒）的化学分析。 可能的应用跨越许多学科，包括化学，生物学，物理学，聚合物科学，医学和材料科学，使新的探测器具有潜在的商业化吸引力。 参与的学生将接触到多学科研究，包括在劳伦斯利弗莫尔国家实验室的低温物理培训。 为了实现这些气相离子化学测量，超导隧道结（STJ）低温探测器正在通过增加像素的大小和数量进行改进，从而导致检测面积增加10倍。 钽-STJ和铍-STJ都在研究中。 这些探测器正在与先进的高速电子设备相结合，以改善到达时间和能量测量，并在两台质谱仪上进行测试：一台配备基质辅助激光解吸电离（MALDI）的飞行时间分析仪和一台配备MALDI和电喷雾电离（ESI）的高m/z离子阱。 这应该能够基于亚稳态碎裂生成质谱。 该研究正在探索能量响应是否在形状测量中具有额外的分析实用性（例如，天然蛋白质）和密度（例如，对于金纳米颗粒）。 STJ能量分辨率的提高及其分析较大大分子的能力可能会导致MS测量的范式转变，特别是在聚合物和大小纳米颗粒研究领域。 关于ESI和MALDI的新的基础知识应该随之而来，提供更好的洞察各自的高m/z限制。

Professor Mark E. Bier and his students at Carnegie Mellon University are supported by the Chemical Measurement and Imaging (CMI) Program of the Division of Chemistry at the NSF to conduct fundamental studies targeting improved detectors for mass spectrometry (MS, a major tool for characterizing chemicals and biochemicals). Recent advances in data and detector technologies have enabled improvements in both the speed of response and energy resolution attainable when detecting ions during MS analysis. The Bier group is investigating whether measurement of the energy deposited when an ion impacts a detector can be related to the structure of the ion - information critical for understanding how molecules function. This could enable, for example, improved chemical analysis of macromolecular complexes such as virus particles and synthetic nanoparticles. Possible applications span many disciplines, including chemistry, biology, physics, polymer science, medicine and materials science, making the new detector potentially attractive for commercialization. Students involved are exposed to multidisciplinary research, including training in low-temperature physics at Lawrence Livermore National Laboratory. To enable these gas phase ion chemistry measurements, superconducting tunnel junction (STJ) cryodetectors are being improved by increasing the size and number of pixels, resulting in a 10X larger detection area. Both tantalum-STJs and niobium-STJs are being investigated. The detectors are being combined with advanced high-speed electronics to improve arrival time and energy measurements, and tested on two mass spectrometers: a time-of-flight analyzer equipped with matrix-assisted laser desorption ionization (MALDI) and a high m/z ion trap equipped with both MALDI and electrospray ionization (ESI). This should enable generation of mass spectra based on metastable fragmentation. The research is exploring whether the energy response has additional analytical utility in the measurement of shape (e.g., of native proteins) and density (e.g., for gold nanoparticles). The improved energy resolution of STJs and their ability to analyze larger macromolecules could result in a paradigm shift for MS measurements, especially in the fields of polymer and small and large nanoparticle research. New fundamental knowledge about ESI and MALDI should ensue, providing better insight into the respective high m/z limits.