Korea Basic Science Institute, Mass Spectrometry Team, Ochang, Republic of Korea.
J Am Soc Mass Spectrom. 2010 Mar;21(3):386-92. doi: 10.1016/j.jasms.2009.11.001. Epub 2009 Nov 6.
Positive-ion atmospheric pressure chemical ionization (APCI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analyses of petroleum sample were performed with higher sensitivity by switching the solvent composition from toluene and methanol or acetonitrile to a one-component system consisting only of toluene. In solvent blends, molecular ions were more abundant than were protonated ions with increasing percentages of toluene. In 100% toluene, the double-bond equivalence (DBE) distributions of molecular ions obtained by APCI MS for each compound class were very similar to those obtained in dopant assisted atmospheric pressure photo ionization (APPI) MS analyses. Therefore, it was concluded that charge-transfer reaction, which is important in toluene-doped APPI processes, also plays a major role in positive-ion APCI. In the DBE distributions of S(1), S(2), and SO heteroatom classes, a larger enhancement in the relative abundance of molecular ions at fairly specific DBE values was observed as the solvent was progressively switched to toluene. This enhanced abundance of molecular ions was likely dependent on molecular structure.
采用正离子大气压化学电离（APCI）傅里叶变换离子回旋共振质谱（FT-ICR MS）对石油样品进行分析时，通过将溶剂组成从甲苯和甲醇或乙腈切换为仅由甲苯组成的单一组分体系，可获得更高的灵敏度。在溶剂混合物中，随着甲苯比例的增加，分子离子比质子化离子更为丰富。在 100%甲苯中，通过 APCI MS 获得的每个化合物类别的分子离子的双键等价物（DBE）分布与在掺杂剂辅助大气压光电离（APPI）MS 分析中获得的分布非常相似。因此，可以得出结论，在甲苯掺杂的 APPI 过程中很重要的电荷转移反应也在正离子 APCI 中起主要作用。在 S(1)、S(2)和 SO 杂原子类别的 DBE 分布中，随着溶剂逐渐切换为甲苯，在相当特定的 DBE 值处，分子离子的相对丰度会显著增强。这种分子离子丰度的增强可能取决于分子结构。
