Ambient ionization techniques provide a way to sample materials via creation of ions in the air. However, transferring and focusing of these ions is typically done in the reduced pressure environment of the mass spectrometer. Spray-based ambient ionization sources require relatively large distances between the source and mass spectrometer inlet for effective desolvation, resulting in a small fraction of the ions being collected. To increase the efficiency of ion transfer from atmosphere to vacuum, 3D-printed focusing devices made of conductive carbon nanotube doped polymers have been designed and evaluated for ion focusing in air. Three main classes of electrodes are considered: (i) conic section electrodes (conical, ellipsoidal, and cylindrical), (ii) simple conductive and non-conductive apertures, and (iii) electrodes with complex geometries (straight, chicane, and curved). Simulations of ion trajectories performed using the statistical diffusion simulation (SDS) model in SIMION showed a measure of agreement with experiment. Cross-sectional images of ion beams were captured using an ion detecting charge-coupled device (IonCCD). After optimization, the best arrangements of electrodes were coupled to an Agilent Ultivo triple quadrupole to record mass spectra. Observations suggest that electrode geometry strongly influences ion trajectories in air. Non-conductive electrodes also assisted in focusing, due to charge buildup from ion deposition. We also observed minimal spreading of the ion packet after exiting the focusing electrodes indicating that atmospheric collisions do not reduce collimation of the beam. The study suggests that high pressures need not be viewed as a hindrance to ion transport, but as a potentially useful force.

中文翻译：

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使用 3D 打印电极在露天进行离子操作。

环境电离技术提供了一种通过在空气中产生离子来对材料进行采样的方法。然而，这些离子的转移和聚焦通常是在质谱仪的减压环境中完成的。基于喷雾的环境电离源需要源和质谱仪入口之间的距离相对较大才能有效去溶剂化，从而导致收集到一小部分离子。为了提高从大气到真空的离子转移效率，已经设计并评估了由导电碳纳米管掺杂聚合物制成的 3D 打印聚焦装置，用于在空气中进行离子聚焦。考虑了三类主要电极：(i) 圆锥截面电极（圆锥形、椭圆形和圆柱形），(ii) 简单的导电和非导电孔，(iii) 具有复杂几何形状（直线、减速弯和弯曲）的电极。使用 SIMION 中的统计扩散模拟 (SDS) 模型执行的离子轨迹模拟显示出与实验一致的度量。使用离子检测电荷耦合器件 (IonCCD) 捕获离子束的横截面图像。优化后，将最佳电极排列与 Agilent Ultivo 三重四极杆耦合以记录质谱。观察表明，电极几何形状强烈影响空气中的离子轨迹。由于离子沉积的电荷积累，非导电电极也有助于聚焦。我们还观察到在离开聚焦电极后离子包的扩散最小，表明大气碰撞不会减少光束的准直。