Application of Atmospheric Pressure Photoionization H/D-exchange Mass Spectrometry for Speciation of Sulfur-containing Compounds

Acter, Thamina,Kim, Donghwi,Ahmed, Arif,Ha, Ji-Hyoung,Kim, Sunghwan Springer US 2017 Journal of the American Society for Mass Spectrome Vol.28 No.8

<P>Herein we report the observation of atmospheric pressure in-source hydrogen-deuterium exchange (HDX) of thiol group for the first time. The HDX for thiol group was optimized for positive atmospheric pressure photoionization (APPI) mass spectrometry (MS). The optimized HDX-MS was applied for 31 model compounds (thiols, thiophenes, and sulfides) to demonstrate that exchanged peaks were observed only for thiols. The optimized method has been successfully applied to the isolated fractions of sulfur-rich oil samples. The exchange of one and two thiol hydrogens with deuterium was observed in the thiol fraction; no HDX was observed in the other fractions. Thus, the results presented in this study demonstrate that the HDX-MS method using APPI ionization source can be effective for speciation of sulfur compounds. This method has the potential to be used to access corrosion problems caused by thiol-containing compounds.</P> [FIG OMISSION]</BR>

Optimization and Application of APCI Hydrogen-Deuterium Exchange Mass Spectrometry (HDX MS) for the Speciation of Nitrogen Compounds

Acter, Thamina,Cho, Yunju,Kim, Sungji,Ahmed, Arif,Kim, Byungjoo,Kim, Sunghwan Springer New York LLC 2015 Journal of the American Society for Mass Spectrome Vol.26 No.9

<P>A systematic study was performed to investigate the utility of atmospheric pressure chemical ionization hydrogen-deuterium exchange mass spectrometry (APCI HDX MS) to identify the structures of nitrogen-containing aromatic compounds. First, experiments were performed to determine the optimized experimental conditions, with dichloromethane and CH<SUB>3</SUB>OD found to be good cosolvents for APCI HDX. In addition, a positive correlation between the heated capillary temperature and the observed HDX signal was observed, and it was suggested that the HDX reaction occurred when molecules were contained in the solvent cluster. Second, 20 standard nitrogen-containing compounds were analyzed to investigate whether speciation could be determined based on the different types of ions produced from nitrogen-containing compounds with various functional groups. The number of exchanges occurring within the compounds correlated well with the number of active hydrogen atoms attached to nitrogen, and it was confirmed that APCI HDX MS could be used to determine speciation. The results obtained by APCI HDX MS were combined with the subsequent investigation of the double bond equivalence distribution and indicated that resins of shale oil extract contained mostly pyridine type nitrogen compounds. This study confirmed that APCI HDX MS can be added to previously reported chemical ionization, electrospray ionization, and atmospheric pressure photo ionization-based HDX methods, which can be used for structural elucidation by mass spectrometry.</P> [FIG OMISSION]</BR>

Characterization of petroleum‐related natural organic matter by ultrahigh‐resolution mass spectrometry

Acter Thamina,이슬기다운,Uddin Nizam,Mow Kamarum Monira,김성환 대한화학회 2023 Bulletin of the Korean Chemical Society Vol.44 No.4

Because petroleum-related natural organic matter (NOM), such as humic sub- stances, is extremely heterogeneous and complex, characterizing and identify- ing its chemical structure at the molecular level is attracting considerable attention. Among the different techniques for mass analysis, ultrahigh- resolution mass spectrometry methods, such as FT-ICR MS and its coupling with other complementary methods, have proven to be crucial for structurally characterizing complex environmental mixtures owing to their excellent analyt- ical power. In particular, their ultrahigh resolution, unrivaled mass accuracy, remarkable ionization specificity, excellent ion activation, and high degree of flexibility for combination with hybrid instruments offer a reliable platform for analyzing petroleum-NOM molecules. This account, aimed at contributing to the advancement of petroleum-NOM molecule analysis, summarizes the appli- cation of FT-ICR MS with different ionization sources and its coupling with other complementary methods developed by our research group.

Synthesis and Shape Control of Uniform Polymer Microparticles by Tailored Adsorption of Poly(ethylene oxide)-b-Poly(ε-caprolactone) Copolymer

Shahinur Acter,조장우,김정운,변아람,박경호,김진웅 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.5

This paper introduces a straightforward and robust polymerization method for the synthesis of uniform polymer microparticles having controlled surface chemistry as well as tailored particle shapes. Uniform polystyrene (PS) microparticles are produced by dispersion polymerization, in which amphiphilic poly(ethylene oxide)-b-poly(ε-caprolactone) (PEO-b-PCL) copolymers anchor on to the growing polymer particles and stabilize them by steric repulsion. We have observed that, when PEO-b-PCL copolymers are incorporated at the proper concentration range, the total number of particles remains unchanged after the formation of primary particles, which is essential for maintaining size uniformity. Otherwise, nonuniform PS microparticles are produced mainly as a result of the coagulation or secondary formation of particles. To show the diversity of our particle synthesis technology, shape-controlled microparticles, such as dimples and Janus particles, are also produced by using temperature-mediated swelling and phase separation. Finally, we show that PEO-b-PCL copolymers play a key role in regulating the surface wettability of the seed particles, thereby facilitating the formation of anisotropic microparticles.

Analysis of coffee bean with laser desorption ionization high‐resolution mass spectrometry

Cho Eunji,Acter Thamina,Uddin Nizam,Kim Sunghwan 대한화학회 2022 Bulletin of the Korean Chemical Society Vol.43 No.3

This study evaluates the application of laser desorption ionization highresolution mass spectrometry (LDI-HRMS) to identify coffee components. The coffee analysis was performed based on origins, roasting temperatures, and extraction methods. The LDI-HRMS experimental results were compared with electrospray ionization (ESI) HRMS analysis, which revealed major compositional differences of coffee ingredients between LDI and ESI data. It was also observed that bitter components in coffee increased with the increasing roasting temperature, and espresso was found to have more carbohydratederived compounds. This study clearly shows that coffee components can efficiently be identified with LDI. Moreover, a more systematic database can be constructed by combining it with LDI-imaging because LDI is simple, fast, and requires small amount sample consumption.

Enhancement of antimicrobial properties of shoe lining leather using chitosan in leather finishing

Mahmud, Yead,Uddin, Nizam,Acter, Thamina,Uddin, Md. Minhaz,Chowdhury, A.M. Sarwaruddin,Bari, Md. Latiful,Mustafa, Ahmad Ismail,Shamsuddin, Sayed Md. Techno-Press 2020 Advances in materials research Vol.9 No.3

In this study, a chitosan based coating method was developed and applied on the shoe lining leather surface for evaluating its inhibition to bacterial and fungal attacks. At first, chitosan was prepared from raw prawn shells and then the prepared chitosan solution was applied onto the leather surface. Secondly, the characterization of the prepared chitosan and chitosan treated leather was performed by solubility test, ATR-FTIR, XRD pattern, SEM and TGA. Evaluation of antimicrobial efficacy of chitosan was assessed against two gram positive, two gram negative bacteria and a reputed fungi by agar diffusion test. The results of this study demonstrated that chitosan took place in both the surface of collagen fibres and inside the collagen matrix of crust leather. The chitosan showed strong antimicrobial activities against all the tested microorganisms and the inhibition increased with increasing percentage of chitosan. Therefore, the prepared chitosan in this study can be an environment friendly biocide, which functions simultaneously against different spoilage bacteria and fungi on the finished leather surface. Thus by using the prepared chitosan in shoe lining leather, the possibility of microbial attack during shoe wearing can be minimized which is one of the important hygienic requirements of footwear.

Systematic Investigation into the Differences in the (+) APPI Efficiencies of Positional (Ortho, Meta, and Para) Isomers

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.