基于傅里叶变换-离子回旋共振质谱的离子碰撞截面测量方法及应用

Method and Applications of Ion Collision Cross Section Measurement Based on Fourier Transform-Ion Cyclotron Resonance

  • 摘要: 傅里叶变换-离子回旋共振质谱(FT-ICR MS)具有较高的分辨率和串联质谱分析能力。离子在分析池中做回旋运动时,镜像电流会因离子与中性分子发生碰撞而逐渐衰减。基于此,通过选择合适的理论模型,并结合相应的算法,可推算出离子的碰撞截面(CCS)。该方法无需增加仪器硬件成本,可通过直接分析高分辨质谱数据获取离子结构信息。近年来,随着FTICR MS仪器的发展和推广,该方法得到快速发展。本文综述了此类方法使用的碰撞模型、利用时域和频域信号进行数据分析的不同方法及特点,虽然提供的离子CCS数据的可靠性和准确度有待进一步提高,但在离子的动态CCS测量以及离子异构化的研究中表现出独特优势。该方法可进一步与离子淌度技术相结合,借助FTICR MS较高的质量分辨能力和离子操控能力,提供多维度的离子结构信息。

     

    Abstract: The measurement of gas phase collision cross section (CCS) of ions can provide complementary structure information to those typically obtained from mass spectrometry or tandem mass spectrometry. Thus, the ion mobility spectrometry is typically coupled with a mass spectrometer to achieve the advantage after the combination. Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) is characterized by its ultra high resolution and tandem mass spectrometry capabilities. Due to the collisions with neutral molecules, the image current caused by the cyclotron motion of ions in the analysis cell gradually decays under high vacuum condition. Based on this feature, the CCS of ions can be calculated by selecting an appropriate theoretical model and combining with the corresponding algorithm. This method can be directly applied to obtain the value of CCS of the selected ion through the analysis of high-resolution mass spectrometry data without increasing the cost of instrument hardware. With the development and promotion of FT-ICR MS instruments in recent years, such methods have developed rapidly in the past decade and have attracted extensive attention. There are three different ionneutral collision models (Langevin collision model, hardsphere collision model and energetic hardsphere model) which have been applied to connect ion CCS and image current of FT-ICR MS instruments. Time-domain analysis, frequency-domain analysis and time-frequency analysis are three types of data analysis method used to measure ion CCS based on FT-ICR MS. Although the reliability and accuracy of the CCS data provided by such methods need to be further improved, it has been demonstrated its unique advantages in the dynamic CCS measurement and potentials in isomerization study. Such methods can be further combined with ion mobility technology to provide multidimensional ion structure information with the help of FT-ICR′s superior mass resolution and superior ion manipulation capabilities.

     

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