A key aspect of reduced pressure ion mobility spectrometry (IMS) experiments is to identify experimental conditions that minimize the role of collisional energy transfer that allows for assessing effective ion-neutral collision cross sections of metabolites, peptides, and proteins in "native-like" or compact states. Across two separate experimental campaigns using a prototype trapped ion mobility spectrometer (TIMS) coupled to a time-of-flight mass spectrometer, we present independent findings that support the results recently published by Morsa et al. using a different set of thermometer ions (Morsa et al. Anal. Chem. 2020, 92 (6), 4573-4582). First, using five para-substituted benzylammonium ions, we conducted survival yield experiments to assess ion internal energy across different experimental settings. Results from the present set of experiments illustrate that greater ion heating occurs at lower pressures and higher voltage settings applied to the TIMS. At the "softest" settings where the benzylammonium thermometer ions have an effective average energy of 1.73 eV, we observe the majority of bradykinin in the compact state. Under more extreme operating conditions where the energy of the benzylammonium ions varies from 1.83 to 1.86 eV, the bradykinin transitions from the compact to the elongated state. In addition to independently confirming the findings of Morsa et al., we also report the mobilities for the benzylammonium parent and fragment ions using the tandem drift-tube-TIMS calibration procedure described by Naylor et al. ( J. Am. Soc. Mass Spectrom. 2019, 30 (10), 2152-2162).

中文翻译：

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使用苯甲酸铵温度计离子对捕集离子迁移谱源条件的评估。

减压离子迁移谱（IMS）实验的一个关键方面是确定实验条件，以最小化碰撞能量转移的作用，从而评估“天然样”中代谢物，肽和蛋白质的有效离子中性碰撞截面。或紧凑状态。在使用原型捕获离子迁移谱仪（TIMS）与飞行时间质谱仪耦合的两个单独的实验活动中，我们提出了独立的发现，以支持Morsa等人最近发表的结果。使用一组不同的温度计离子（Morsa等人，Anal。Chem。2020，92（6），4573-4582）。首先，我们使用五个对位取代的苄基铵离子，进行了存活率实验，以评估不同实验环境下的离子内部能量。来自当前实验组的结果表明，在施加于TIMS的较低压力和较高电压设置下会发生更大的离子加热。在“最软”设置下，苄基铵温度计离子的有效平均能量为1.73 eV，我们观察到大多数缓激肽处于紧凑状态。在更极端的操作条件下，苄基铵离子的能量在1.83至1.86 eV之间变化，缓激肽从紧密状态转变为伸长状态。除了独立证实Morsa等人的发现，我们还使用Naylor等人描述的串联漂移管-TIMS校准程序报告了苄基铵母体和碎片离子的迁移率。（J.Am.Soc.Mass Spectrom.2019，30（10），2152-2162）。