Improved abundance sensitivity of molecular ions in positive-ion APCI MS analysis of petroleum in toluene |
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Authors: | Young Hwan Kim Sunghwan Kim |
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Institution: | 1.Korea Basic Science Institute,Mass Spectrometry Team,Ochang,Republic of Korea;2.Department of Chemistry,Kyungpook National University,Daegu,Republic of Korea |
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Abstract: | 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 S1, S2, 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. |
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Keywords: | |
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