Novel proton transfer reaction-mass spectrometry by using protonated molecules as a primary ion

研究了一种用于质子转移反应（PTR）电离的两级离子源，以实现对特定挥发性有机化合物（VOCs）的质谱检测，其选择性优于常用的基于H3 O ^+单步PTR电离的PTR-MS仪器。两级PTR离子源通过H_3O^+和选定的VOC之间的初始PTR产生除H_3O ^+之外的试剂离子，然后仅对质子亲合力大于试剂VOC亲合力的VOC进行第二次PTR电离。丙酮使用两级PTR-MS，我们区分异构体VOCs的质子亲和力的差异。该技术已应用于异戊二烯氧化气室实验和二次有机气溶胶分析。

A two-stage ion source for proton transfer reaction (PTR) ionization was investigated in order to achieve more selective mass spectrometric (MS) detection of selected volatile organic compounds (VOCs) than that achieved with commonly used PTR-MS instruments, which are based on single-step PTR ionization with H_3O^+. The two-stage PTR ion source generated reagent ions other than H_3O^+ by an initial PTR between H_3O^+ and a selected VOC, and then a second PTR ionization occurred only for VOCs with proton affinities larger than the affinity of the reagent VOC. Acetone Using two-stage PTR-MS, we differentiated isomeric VOCs by means of differences in their proton affinities. This technique was applied to chamber experiment of isoprene-oxidation and to analysis of secondary organic aerosol.