Wyche Kevin P, Blake Robert S, Willis Kerry A, Monks Paul S, Ellis Andrew M
Department of Chemistry, University of Leicester, Leicester LE1 7RH, UK.
Rapid Commun Mass Spectrom. 2005;19(22):3356-62. doi: 10.1002/rcm.2202.
The technique of proton transfer reaction mass spectrometry (PTR-MS) couples a proton transfer reagent, usually H3O+, with a drift tube and mass spectrometer to determine concentrations of volatile organic compounds. Here we describe a first attempt to use chemical ionization (CI) reagents other than proton transfer species inside a PTR-MS instrument. The ability to switch to other types of CI reagents provides an extra dimension to the technique. This capability is demonstrated by focusing on the ability to distinguish several isobaric aldehydes and ketones, including the atmospherically important molecules methacrolein and methyl vinyl ketone. Two CI reagents were selected, H3O+ and NO+, both being cleanly generated in a low intensity radioactive source prior to injection into the drift tube. By recording spectra with both of these reagents, the contributions from different isobaric molecules can be separated by virtue of their unique spectrometric 'fingerprints'. The work demonstrates that this form of instrumentation is not restricted to proton transfer reagents and is the basis of a more general technique, chemical ionization reaction mass spectrometry (CIRMS).
质子转移反应质谱法（PTR-MS）技术将质子转移试剂（通常为H3O+）与漂移管和质谱仪相结合，以测定挥发性有机化合物的浓度。在此，我们描述了在PTR-MS仪器内部使用除质子转移物种之外的化学电离（CI）试剂的首次尝试。切换到其他类型CI试剂的能力为该技术增添了一个新维度。通过专注于区分几种同量异位醛和酮的能力，包括对大气重要的分子甲基丙烯醛和甲基乙烯基酮，展示了这种能力。选择了两种CI试剂，H3O+和NO+，它们均在注入漂移管之前由低强度放射源纯净地产生。通过用这两种试剂记录光谱，不同同量异位分子的贡献可凭借其独特的光谱“指纹”得以分离。这项工作表明，这种形式的仪器不限于质子转移试剂，并且是一种更通用技术——化学电离反应质谱法（CIRMS）的基础。
