Washington State University, Department of Chemistry, P.O. Box 644630, Pullman, Washington 99164, United States.
Anal Chem. 2012 Jun 5;84(11):4858-65. doi: 10.1021/ac300452j. Epub 2012 May 23.
Security and military applications of analytical techniques demand a small, rugged, reliable instrument that has traditionally been served well by atmospheric pressure ion mobility spectrometry (IMS) systems. Modern threats stipulate these instruments must reliably operate in increasingly complex environments. Previous work has demonstrated that increasing the pressure of an IMS drift tube has the potential to increase the resolving power of IMS, but operation at low temperatures resulted in a leveling of the measured resolving power as a function of pressure. By creating a novel aperture grid/Faraday plate design, a high-pressure IMS (HPIMS) system has been created that maintains a resolving power efficiency of 80% regardless of the pressure applied to the cell. This allows previously unattainable resolving powers to be achieved utilizing a small (10.7 cm) IMS cell. Using high pressure, a stand-alone IMS cell of 10.7 cm length has demonstrated a resolving power of 102 when operated at 2.5 atm. An increase in peak-to-peak resolution was also noted as pressure increased. Finally, the slope of the resulting inverse mobility/pressure curve for a single analyte has been shown to be proportional to the collision-cross-section of the analyte of interest, providing a novel method for the calculation of collision-cross-section of target ions from the HPIMS data.
分析技术在安全和军事领域的应用需要一种小型、坚固、可靠的仪器，而常压离子淌度谱（IMS）系统在传统上很好地满足了这一需求。现代威胁规定这些仪器必须能够在日益复杂的环境中可靠运行。先前的工作已经证明，增加 IMS 漂移管的压力有提高 IMS 分辨率的潜力，但在低温下操作会导致测量分辨率随压力的增加而趋于平稳。通过创建一种新颖的孔径格栅/法拉第板设计，创建了一种高压 IMS（HPIMS）系统，无论施加到单元上的压力如何，该系统都能保持 80%的分辨率效率。这使得以前无法实现的分辨率可以利用小尺寸（10.7 厘米）的 IMS 单元来实现。使用高压，当在 2.5 大气压下操作时，长度为 10.7 厘米的独立 IMS 单元已显示出 102 的分辨率。还注意到随着压力的增加，峰峰值分辨率也有所提高。最后，对于单个分析物，所得逆淌度/压力曲线的斜率已被证明与分析物的碰撞截面成正比，从而为从 HPIMS 数据计算目标离子的碰撞截面提供了一种新方法。
