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Arif Ahmed,Syful Islam,Nissa Nurfajrin Solihat,Thamina Acter,김성환 대한화학회 2019 Bulletin of the Korean Chemical Society Vol.40 No.11
Understanding the underlying principle behind the ionization technique is important for improving the sensitivity and selectivity of mass spectrometry (MS), and analyte?solvent interactions are important factors that affect the ionization process. In this study, analyte?solvent interactions were investigated using a series of ortho, meta, and para isomers, (+) APPI-MS, and computational chemistry. Experimental results reveal that isomers can have vastly different ionization efficiencies, despite their identical elemental formulas and functional groups. To better understand the reasons behind these observations, various analyte?solvent radical-ion complexes were investigated by quantum mechanical techniques, and the factors that contribute to the differences in the ion-formation behavior of these compounds were thoroughly investigated.
Elucidating H/D-Exchange Mechanism of Active Hydrogen in Aniline and Benzene-1,2-dithiol
( Arif Ahmed ),( Syful Islam ),( Sunghwan Kim ) 한국질량분석학회 2021 Mass spectrometry letters Vol.12 No.4
In this study, the hydrogen/deuterium (HDX) exchange mechanism of active hydrogen, nitrogen, and sulfur-containing polycyclic aromatic hydrocarbon (PAH) dissolved in toluene and deuterated methanol by atmospheric pressure photoionization (APPI) is investigated. The comparison of the data obtained using APPI suggests that aniline and benzene-1,2-dithiol contain two exchanging hydrogens. The APPI HDX that best explains the experimental findings was investigated with the use of quantum mechanical calculations. The HDX mechanism is composed of a two-step reaction: in the first step, analyte radical ion gets deuterated, and in the second step, the hydrogen transfer occurs from deuterated analyte to de-deuterated methanol to complete the exchange reaction. The suggested mechanism provides fundamentals for the HDX technique that is important for structural identification with mass spectrometry. This paper is dedicated to Professor Seung Koo Shin for his outstanding contributions in chemistry and mass spectrometry.