Biological Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA.
Anal Chem. 2009 Aug 1;81(15):6489-95. doi: 10.1021/ac900892u.
The maximum electric field intensity (E) in field asymmetric waveform ion mobility spectrometry (FAIMS) analyses was doubled to E > 60 kV/cm. In earlier devices with >0.5 mm gaps, such strong fields cause electrical breakdown for nearly all gases at ambient pressure. As the Paschen curves are sublinear, thinner gaps permit higher E: here, we established 61 kV/cm in N(2) using microchips with 35 microm gaps. As FAIMS efficiency is exceptionally sensitive to E, such values can in theory accelerate analyses at equal resolution by over an order of magnitude. Here we demonstrate FAIMS filtering in approximately 20 micros or approximately 1% of the previously needed time, with a resolving power of about half that for "macroscopic" units but sufficing for many applications. Microscopic gaps enable concurrent ion processing in multiple (here, 47) channels, which greatly relaxes the charge capacity constraints of planar FAIMS designs. These chips were integrated with a beta-radiation ion source and charge detector. The separation performance is in line with first-principles modeling that accounts for high-field and anisotropic ion diffusion. By extending FAIMS operation into the previously inaccessible field range, the present instrument advances the capabilities for research into ion transport and expands options for separation of hard-to-resolve species.
在非对称电场波形离子淌度谱（FAIMS）分析中，最大电场强度（E）增加到 E > 60 kV/cm。在过去的间隙大于 0.5 毫米的设备中，如此强的电场几乎会导致所有气体在环境压力下发生电击穿。由于 Paschen 曲线呈亚线性，因此更薄的间隙允许更高的 E：在这里，我们使用间隙为 35 微米的微芯片在 N2 中建立了 61 kV/cm。由于 FAIMS 效率对 E 非常敏感，因此这些值理论上可以在相同分辨率下加速分析，速度提高一个数量级以上。在这里，我们展示了 FAIMS 过滤大约 20 微秒或之前所需时间的 1%，分辨率约为“宏观”单元的一半，但足以满足许多应用。微观间隙允许在多个（这里是 47 个）通道中同时进行离子处理，这大大放宽了平面 FAIMS 设计的电荷容量限制。这些芯片与β辐射离子源和电荷探测器集成在一起。分离性能与考虑高场和各向异性离子扩散的第一性原理模型一致。通过将 FAIMS 操作扩展到以前无法进入的场范围，本仪器提高了离子传输研究的能力，并扩展了难以分离的物种的分离选择。
