Mathurin JC, Faye T, Brunot A, Tabet JC, Wells G, Fuche C
Laboratoire de Chimie Structurale Organique et Biologique, CNRS UMR 7613, Universite Pierre et Marie Curie, Paris, France.
Anal Chem. 2000 Oct 15;72(20):5055-62. doi: 10.1021/ac000171m.
A new combination of a dual EI/CI ion source with a quadrupole ion trap mass spectrometer has been realized in order to efficiently produce negative ions in the reaction cell. Analysis of volatile compounds was performed under negative ion chemical ionization (NICI) during a reaction period where selected reactant negative ions, previously produced in the external ion source, were allowed to interact with molecules, introduced by hyphenated techniques such as gas chromatography. The O2*-, CH3O-, and Cl- reactant ions were used in this study to ensure specific ion/molecule interactions such as proton transfer, nucleophilic displacement, or charge exchange processes, respectively leading to even-electron species, i.e., deprotonated [M - H]- molecules, diagnostic [M - R]- ions, or odd-electron M*- molecular species. The reaction orientation depends on the thermochemistry of reactions within kinetic controls. First analytical results are presented here for the trace-level detection of several contaminants under NICI/Cl- conditions. Phosphorus-containing compounds (malathion, ethyl parathion, and methyl parathion as representative for pesticides) and nitro-containing compounds (2,4,6-trinitrotoluene for explosive material) have been chosen in order to explore the analytical ability of this promising instrumental coupling.
为了在反应池中高效产生负离子，实现了双EI/CI离子源与四极杆离子阱质谱仪的新组合。在负离子化学电离（NICI）条件下，对挥发性化合物进行分析。在反应期间，预先在外离子源中产生的选定反应物负离子与通过气相色谱等联用技术引入的分子相互作用。本研究中使用O2* - 、CH3O - 和Cl - 反应物离子，分别确保特定的离子/分子相互作用，如质子转移、亲核取代或电荷交换过程，分别产生偶电子物种，即去质子化的[M - H]-分子、诊断性的[M - R]-离子或奇电子M* - 分子物种。反应取向取决于动力学控制下反应的热化学。本文给出了在NICI/Cl - 条件下对几种污染物进行痕量检测的初步分析结果。为了探索这种有前景的仪器联用的分析能力，选择了含磷化合物（马拉硫磷、对硫磷和甲基对硫磷作为农药的代表）和含硝基化合物（2,4,6 - 三硝基甲苯作为爆炸物材料）。
