Development of a Proton Transfer Reaction Linear Ion Trap for Fast Atmospheric Pollutant Detection

普渡大学的Paul Shepson和Scott McLuckey教授以及因斯布鲁克大学的Armin Hansel教授得到了分析和表面化学以及大气化学计划的支持，以开发和评估一种用于快速灵敏地检测大气污染物的新型仪器。 这项研究的动机是，植物中的挥发性有机化合物以重要的方式参与对流层臭氧的产生，这是一种重要的温室气体。 因此，非常需要关于气体与森林生态系统交换的定量资料。 该仪器被称为质子转移反应线性离子阱，是一种组合流管反应器和线性四极杆质谱仪，具有独特的新设计，使用具有适当施加电势的端板，能够在四极杆的轴内捕获离子。 分析物离子在允许与质子反应的流管中产生，然后采样到质谱仪;已知的反应动力学可以允许在没有校准标准的情况下进行定量检测。 然后可以用施加的AC电势激发选定的离子，导致碰撞诱导解离，并获得MS/MS谱。 使用涡动协方差通量技术将有可能进行通量测量。 该项目涉及质谱、仪器开发和大气化学专家组之间的合作努力。 开发的仪器将在普渡大学进行测试，然后在密歇根州北方的一个森林站点进行现场测试，作为森林-大气相互作用的大规模研究（PROPHET）的一部分。 第一代仪器将用于测量生物异戊二烯的氧化产物（甲基乙烯基酮和甲基丙烯醛），并测量森林树冠的异戊二烯通量。 该项目有可能影响包括痕量检测和大气化学在内的多个领域。 挥发性有机化合物（VOC）在介导二氧化碳水平上升的影响方面的作用还没有得到很好的理解。 因此，这项研究是了解和预测全球表面温度变化的一个重要因素。

Professors Paul Shepson and Scott McLuckey of Purdue University and Professor Armin Hansel of the University of Innsbruck are supported by the Analytical and Surface Chemistry and Atmospheric Chemistry Programs to develop and evaluate a novel instrument for fast and sensitive detection of atmospheric pollutants. The research is motivated by the fact that volatile organic compounds from vegetation participate in significant ways in the production of tropospheric ozone, which is an important greenhouse gas. There is thus a great need for quantitative information about exchange of gases with forest ecosystems. The instrument, called a Proton Transfer Reaction Linear Ion Trap, is a combination flow tube reactor and linear quadrupole mass spectrometer, with a unique new design that uses end plates with appropriate applied potentials that enable trapping of ions within the axis of the quadrupole rods. Analyte ions are produced in a flow tube that allows for reaction with protons, followed by sampling to the mass spectrometer; the known reaction kinetics can allow for quantitative detection without calibration standards. Selected ions can then be excited with an applied AC potential, resulting in collision induced dissociation, and acquisition of MS/MS spectra. Flux measurements will be possible using the eddy covariance flux technique. This project involves a collaborative effort between groups expert in mass spectrometry, instrument development and atmospheric chemistry. The developed instrumentation will be tested at Purdue and then field tested at a forest site in northern Michigan as part of a large-scale study (PROPHET) of forest-atmosphere interactions. The first generation instrument will be used to conduct measurements of the oxidation products (methyl vinyl ketone and methacrolein) of biogenic isoprene, and to conduct measurements of the fluxes of isoprene from the forest canopy. The project has the potential to impact several fields including trace detection and atmospheric chemistry. The role of volatile organic compounds (VOCs) in mediating the impacts of rising carbon dioxide levels is not well understood. This research is thus an important element in understanding and predicting global surface temperature changes.