• Mass Spectrometry Letters
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• v.6 no.4
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• pp.105-111
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• 2015

Sixteen compounds of Neobalanocarpus heimii were successfully identified directly from their plant extract using a triple quadrupole LC-MS/MS system. In order to fulfil the objectives of this work, a series of stilbene oligomers of various degrees of condensation were isolated and their structure are characterized. Out of these, four are resveratrol dimers, three trimers, and nine tetramers. The isolation process was done on a fully automated semi-preparative HPLC system. Their structures were elucidated on the basis of 1D- and 2D-NMR as well as MS data. The mass fragmentation patterns of the compounds were recorded and a retrievable in-house library was built to keep the data. In order to demonstrate the potential of this approach, the polyphenolic crude extract was analysed with the LC-MS/MS system and the MS/MS spectra extracted for each chromatographic peak of interest. The fragmentation patterns were compared with those of anticipated pure compounds that were previously recorded. All compounds were successfully identified. It is therefore believed that the LC-MS/MS potential for dereplication of structurally similar compounds in a crude mixture was thus firmly established.

• Mass Spectrometry Letters
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• v.7 no.4
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• pp.96-101
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• 2016

To determine the influence of the cationization agent on the collision activated dissociation (CAD) fragmentation behavior of oligosaccharides, the CAD spectra of the singly protonated, sodiated oligosaccharides and singly sodiated and dibenzo-18-crown-6 ether conjugated oligosaccharides were carefully compared. Each of these three different species showed quite different fragmentation spectra. The comparison of singly protonated and sodiated oligosaccharide CAD spectra revealed that different cationization agents affected the cationization agent adduction sites as well as the fragmentation sites within the oligosaccharides. When the mobility of $Na^+$ was limited by the dibenzo-18-crown-6 ether encapsulation agent, the examined linear oligosaccharides showed fragmentation patterns quite different from the unmodified ones. For the dibenzo-18-crown-6 ether conjugated oligosaccharides, the charge-remote fragmentation pathways were more likely to be activated than the chargedirected pathways. This work demonstrates that dibenzo-18-crown-6 ether conjugation can potentially provide a route to selectively activate the charge-remote fragmentation pathways, albeit to a limited extent, in tandem mass spectrometry studies.

• Mass Spectrometry Letters
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• v.4 no.4
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• pp.79-82
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• 2013

Various types of alkaloids observed in several herbal medicines were analyzed by electrospray ionization tandem mass spectrometry in positive ion mode. In the present study, MS/MS spectralpatterns were investigated for eight-types of alkaloids (aporpine, protoberberine, tetrahydroprotoberberine, benzylisoquinoline, protopine, phthalide, morpine, and bisbenzylisoquinoline). For aporpine- and protoberberine-type alkaloids, main fragmentations occurred at substituted groups on rigid ring structures, not showing ring fusion. Interesting fragmentations due to iminolization and retro-Diels-Alder (RDA) reaction were observed in MS/MS spectra of protopine- and tetrahydroprotobereberine-type alkaloids. Also, several types of fragmentations such as inductive cleavage and ${\alpha}$-cleavage, or bond cleavage between two ring structures were observed depending on their structural characteristics. These fragmentation patterns are expected to allow instant classification of the specific alkaloid type in various MS/MS spectra of alkaloids.

• Mass Spectrometry Letters
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• v.4 no.2
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• pp.30-33
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• 2013

Chalcones are naturally occurring, biologically active molecules generating interest from a wide range of research applications including synthetic methodology development, biological activity investigation and studying fragmentation patterns. In this article, a series of chalcones has been synthesized and their fragmentation behavior was studied using modern ambient ionization technique Direct Analysis in Real Time (DART). DART ion source connected with an ion trap mass spectrometer was used for the fragmentation of various substituted chalcones. The chalcones were introduced to the DART source using a glass capillary without sample preparation step. All the chalcones showed prominent molecular ion peaks $[M]^{{\cdot}+}$ corresponding to the structures. Multistage mass spectral data $MS^n$ ($MS^2$ and $MS^3$) were collected for all the chalcones studied. The chalcones with substitutions at 3, 4 or 5 positions gave product ion peaks with the loss of a phenyl radical ($Ph^{\cdot}$) by radical initiated ${\alpha}$-cleavage, while substitution at 2 position of chalcone in the A-ring gave a product ion peak with the loss of substituted styryl radical (PhCH = $CH^{\cdot}$). In case of the chalcones with the substituent at 4 positions in A and B rings gave both types of fragmentation patterns. In conclusion, chalcones can be easily characterized using modern DART interface in very short time and efficiently without any cumbersome sample pretreatment.

• Toxicological Research
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• v.29 no.2
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• pp.107-114
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• 2013

Mass spectrometry (MS) is a very powerful instrument that can be used to analyze a wide range of materials such as proteins, peptides, DNA, drugs, and polymers. The process typically involves either chemical or electron (impact) ionization of the analyte. The resulting charged species or fragment is subsequently identified by the detector. Usually, single mass uses source-induced dissociation (SID), whereas mass/mass uses collision-induced dissociation (CID) to analyze the chemical fragmentations Each technique has its own advantages and disadvantages. While CID is most effective for the analysis of pure substances, multiple-step MS is a powerful technique to get structural data. Analysis of veterinary drugs ampicillin, chloramphenicol, ciprofloxacin, and oxytetracycline serves to highlight the slight differences between SID and CID. For example, minor differences were observed between ciprofloxacin and oxytetracycline via SID or CID. However, distinct fragmentation patterns were observed for ampicllin depending on the analysis method. Both SID and CID showed similar fragmentation spectra but different signal intensities for chloramphenicol. There are several factors that can influence the fragmentation spectra, such as the collision energy, major precursor ion, electrospray mode (positive or negative), and sample homogeneity. Therefore, one must select a fragmentation method on an empirical and case-by-case basis.

• Analytical Science and Technology
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• v.6 no.1
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• pp.93-106
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• 1993

Fragmentation patterns on electron impact of 8 chlorinated organophosphorus pesticides were investigated. In most cases, characteristic ions could e identified and the peak clusters due to the $^{35}Cl$ and $^{37}Cl$ isotopes in the fragment ions were found to be highly characteristic. The fragmentation patterns of phosphorus moiety were coincident with previous report in the aspect of mechanism.

• Bulletin of the Korean Chemical Society
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• v.19 no.10
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• pp.1131-1133
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• 1998

• Journal of the Korean Chemical Society
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• v.42 no.3
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• pp.297-301
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• 1998

Linkage positions in oligosaccharides may be obtained by FAB CAD MS/MS (Fast Atom Bombardment Collision Activated Dissociation Mass Spectrometry/Mass Spectrometry). Acetylated derivatives of the linkage-isomeric trisaccharides exhibited more useful product ion patterns than the free trisaccharides and provided specific fragmentation patterns according to linkage positions. The reason for the useful linkage dependent spectra patterns of acetylated forms is related to the ability of each linkage in the oligosaccharides to absorb different levels of collision energy and rotational freedom of the individual glycosidic linkage.

• Bulletin of the Korean Chemical Society
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• v.21 no.8
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• pp.785-792
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• 2000

Mass spectral fragmentations of six chlorinated organophosphorus pesticides were investigated using electron impact mass spectrometry. Understanding the fragmentation pathways, based on the fragment ions of mass spectra, should be useful in the structural elucidation and chemical identification of these compounds. The pro-posed fragmentation pathways were verified by collision-induced dissociation B/E-linked scan spectra. ln most cases,the structures of characteristic fragment ions could be expected by the observation of the peak clusters due to 35Cl and 37Cl isotopes. According to substituted groups on phosphorus atom, phosphate and phospho-rothioate exhibited significantIy differentfragmentation patterns. Especially, phosphate and phosphorothioate with diethyl ester produced more diverse fragment ions than that with dimethyl ester.

• Analytical Science and Technology
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• v.10 no.1
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• pp.9-17
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• 1997

Nitrophenols are a group of important priority pollutants classified by the US Environmental Protection Agency. Reverse-phase liquid chromatographic method combined with mass spectromethy employing atmospheric pressure chemical ionization(APCI) interface is utilized to determine a mixture of nitrophenols in water matrix without any pretreatment. The sensitivity and selectivity for the identification of different kind of nitrophenols is enhanced by the use of selected ion monitoring and cone voltage fragmentation. The fragmentation patterns of nitrophenols are compared with those obtained from the collision induced dissociation(CID) MS/MS technique.