Dramatic Improvement in Sensitivity with Pulsed Mode Charge Detection Mass Spectrometry,Analytical Chemistry

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Dramatic Improvement in Sensitivity with Pulsed Mode Charge Detection Mass Spectrometry
Analytical Chemistry ( IF 6.7 ) Pub Date : 2019-10-07 , DOI: 10.1021/acs.analchem.9b03586
Aaron R Todd ₁ , Martin F Jarrold ₁

Affiliation

Charge detection mass spectrometry (CDMS) is emerging as a valuable tool to determine mass distributions for heterogeneous and high-mass samples. It is a single-particle technique where masses are determined for individual ions from simultaneous measurements of their mass-to-charge ratio (m/z) and charge. Ions are trapped in an electrostatic linear ion trap (ELIT) and oscillate back and forth through a detection cylinder. The trap is open and able to trap ions for a small fraction of the total measurement time so most of the ions (>99.8%) in a continuous ion beam are lost. Here, we implement an ion storage scheme where ions are accumulated and stored in a hexapole and then injected into the ELIT at the right time for them to be trapped. This pulsed mode of operation increases the sensitivity of CDMS by more than 2 orders of magnitude, which allows much lower titer samples to be analyzed. A limit of detection of 3.3 × 10⁸ particles/mL was obtained for hepatitis B virus T = 4 capsids with a 1.3 μL sample. The hexapole where the ions are accumulated and stored is a significant distance from the ion trap so ions are dispersed in time by their m/z values as they travel between the hexapole and the ELIT. By varying the delay time between ion release and trapping, different windows of m/z values can be trapped.

中文翻译：

脉冲模式电荷检测质谱法的灵敏度显着提高

电荷检测质谱 (CDMS) 正在成为确定异质和高质量样品质量分布的重要工具。它是一种单粒子技术，通过同时测量单个离子的质荷比 ( m / z ) 和电荷来确定其质量。离子被捕获在静电线性离子阱 (ELIT) 中，并通过检测圆筒来回振荡。离子阱是打开的，能够在总测量时间的一小部分内捕获离子，因此连续离子束中的大部分离子 (>99.8%) 都会丢失。在这里，我们实施了一种离子存储方案，其中离子累积并存储在六极杆中，然后在正确的时间注入 ELIT 以便捕获它们。这种脉冲操作模式将 CDMS 的灵敏度提高了 2 个数量级以上，从而可以分析滴度低得多的样品。使用 1.3 μL 样品获得乙型肝炎病毒T = 4 衣壳的检测限为 3.3 × 10 ⁸颗粒/mL。积累和存储离子的六极杆距离子阱很远，因此当离子在六极杆和 ELIT 之间行进时，离子会根据其m / z值及时分散。通过改变离子释放和捕获之间的延迟时间，可以捕获不同的m / z值窗口。

更新日期：2019-10-08

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