Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA.
Anal Chem. 2010 Oct 1;82(19):7952-7. doi: 10.1021/ac1014244.
Although oxidation of biogenic volatile organic compounds (BVOCs) plays an important role in tropospheric ozone and secondary organic aerosol production, significant uncertainties remain in our understanding of the impacts of BVOCs on ozone, aerosols, and climate. To quantify BVOCs, the proton-transfer reaction linear ion trap (PTR-LIT) mass spectrometer was previously developed. The PTR-LIT represents an improvement over more traditional techniques (including the proton-transfer reaction mass spectrometer), providing the capability to directly quantify and differentiate isomeric compounds by MS/MS analysis, with better time resolution and minimal sample handling, compared to gas chromatography techniques. Herein, we present results from the first field deployment of the PTR-LIT. During the Program for Research on Oxidants: Photochemistry, Emissions and Transport (PROPHET) summer 2008 study in northern Michigan, the PTR-LIT successfully quantified isoprene, total monoterpenes, and isomeric isoprene oxidation products methyl vinyl ketone and methacrolein at sub-parts per billion (nmol/mol) levels in a complex forest atmosphere. The utility of the fast time response of the PTR-LIT was shown by the measurement of rapid changes in isoprene, methyl vinyl ketone, and methacrolein, concurrent with changing ozone mole fractions. Overall, the PTR-LIT was shown to be a viable field instrument with the necessary sensitivity, selectivity, and time response to provide detailed measurements of BVOC mole fractions in complex atmospheric samples, at trace levels.
尽管生物挥发性有机化合物（BVOCs）的氧化作用在对流层臭氧和二次有机气溶胶的产生中起着重要作用，但我们对 BVOCs 对臭氧、气溶胶和气候的影响的理解仍存在很大的不确定性。为了定量测量 BVOCs，之前开发了质子转移反应线性离子阱（PTR-LIT）质谱仪。与更传统的技术（包括质子转移反应质谱仪）相比，PTR-LIT 代表了一种改进，通过 MS/MS 分析提供了直接定量和区分异构体化合物的能力，与气相色谱技术相比，具有更好的时间分辨率和最小的样品处理。本文介绍了 PTR-LIT 首次野外部署的结果。在北密歇根州的氧化剂研究计划：光化学、排放和运输（PROPHET）2008 年夏季研究中，PTR-LIT 成功地在复杂的森林大气中以亚ppm（nmol/mol）水平定量测量了异戊二烯、总单萜和异戊二烯氧化产物甲基乙烯基酮和甲基丙烯醛。PTR-LIT 的快速时间响应的实用性通过与臭氧摩尔分数同时变化的异戊二烯、甲基乙烯基酮和甲基丙烯醛的快速变化来证明。总的来说，PTR-LIT 被证明是一种可行的现场仪器，具有必要的灵敏度、选择性和时间响应，可在痕量水平下对复杂大气样品中的 BVOC 摩尔分数进行详细测量。
