Fragmentation Patterns In Mass Spectra Research Articles

Quantitative analysis of fatty acids in <em>Prosopis laevigata</em> flour

Ripe mesquite pods are widely consumed by humans and animals in arid and semi-arid areas for their protein, carbohydrate, crude fiber and fat contents. The goal of this work is to identify and to quantify the fatty acid profile of flour from mesquite pods. Structural assignments were confirmed by the analysis of fragmentation patterns of mass spectra obtained by GC-MS. The results showed that 75% of the fatty acids were unsaturated, of which linoleic acid was predominant, while palmitic and stearic acids, and saturated fatty acids were found in minor proportions.

Distinct Fragmentation Pathways of Anticancer Drugs Induced by Charge-Carrying Cations in the Gas Phase.

With the growth of the pharmaceutical industry, structural elucidation of drugs and derivatives using tandem mass spectrometry (MS2) has become essential for drug development and pharmacokinetics studies because of its high sensitivity and low sample requirement. Thus, research seeking to understand fundamental relationships between fragmentation patterns and precursor ion structures in the gas phase has gained attention. In this study, we investigate the fragmentation of the widely used anticancer drugs, doxorubicin (DOX), vinblastine (VBL), and vinorelbine (VRL), complexed by a singly charged proton or alkali metal ion (Li+, Na+, K+) in the gas phase. The drug-cation complexes exhibit distinct fragmentation patterns in tandem mass spectra as a function of cation size. The trends in fragmentation patterns are explicable in terms of structures derived from ion mobility mass spectrometry (IM-MS) and theoretical calculations. Graphical Abstract ᅟ.

Systematic Derivatization of Curcumin and its Effect on Antioxidant Capacity and Action Mechanism. Cyclic Voltammetry and DFT as Tools of Analysis

Eight curcumin derivatives were synthesized by esterification of its phenol groups with first and second generation polyester dendrons (dendronization) or glutaric anhydride (glutarization), in a systematic scheme where mono and disubstitutions were carried out. The dendronization of curcumin (CUR) affects the fragmentation patterns in mass spectra, particularly for the disubstituted OH-terminated second generation derivative (labeled as 2C2), undergoing the cleavage of one of the aromatic rings. This fact may be related to the antioxidant capacity of 2C2, evaluated following its reaction with superoxide (O2•-) by cyclic voltammetry (CV). As opposed to CUR and the rest of its derivatives that react with O2•- via proton transfer reactions, 2C2 reacts with O2•- mainly by hydrogen atom transfer. 2C2 radical scavenging activity versus O2•- is higher than the one observed for CUR. From DFT calculations, independently of the substitution on CUR, the frontier molecular orbitals remain nearly unaltered as compared to CUR. On the other hand, when CUR is dendronized, the electric dipole moment notably changes as a function of the nature of the terminal groups.

Mechanistic investigation of charge-remote and charge-driven fragmentation processes in 2,5-diphenyl-3,4-ethylenedioxythiophene diamidines.

Diphenylfuran diamidines represent an important class of DNA minor groove binders of high therapeutic interest as antitumor and antibacterial agents. This study aimed to investigate fragmentation patterns in mass spectra of four diamidine derivatives with significant antitumor activity, in order to gain more insight into the structures and stability of their putative biological metabolites. Compounds were investigated by electrospray ionization tandem mass spectrometry (ESI-MS/MS) using low-energy collision-induced dissociation (CID). Density functional theory calculations were performed to confirm the main fragmentation paths. The most abundant ion present in mass spectra is the doubly protonated molecule, whereas singly protonated molecules are present to a lesser extent. In the simplest compound, 2,5-bis(4-amidinophenyl)-3,4-ethylenedioxythiophene, the main fragmentation path was loss of ammonia, followed by loss of HCN where possible. The fragmentation of the N-alkyl derivatives (N-isopropyl-, N-isobutyl-, N-cyclopentyl-) includes competition between loss of alkene and the corresponding amine, followed by loss of another alkene and formation of fragment ions present in the pathway of the parent compound. The primary sites of fragmentations of investigated compounds are amidine groups, while breaking the core 3,4-ethylenedioxythiophene ring system does not take place. Fragmentation of the singly protonated molecule [M+H](+) occurs primarily on the charged side of the molecule, but a charge-remote process is energetically viable. The fragmentation mechanism of the alkyl derivatives revealed that singly and doubly protonated molecules cleave to the singly and doubly protonated molecules of the parent compound. Once formed, they are gradually transformed into nitrile. Copyright © 2016 John Wiley & Sons, Ltd.

Gas Chromatography-Mass Spectrometry determination of bioactive components in Annona muricata seed (soursop seed) methanol extract

Traditionally, Annona muricata is been used in the treatment of diseases. Phytocompounds of Annona muricata seed methanol extract were determined by gas chromatography-mass spectrometry analysis. The result obtained from the GC-MS analysis of methanol extract of Annona muricata seed led to identification of four(4) compounds. The components were identified by comparing their retention indices and mass spectra fragmentation patterns with those stored in the National Institute of Standards and Technology (NIST) library. The major constituents reported are hexadecanoic acid (16.39 %), 2,6-dimethyl-1,7-octadien-3-ol (17.50%), 9-octadecanoic acid(53.92%) and nonadecanoic acid (12.19%).

Characterization of Annona muricata stem methanol extract by gas chromatography-mass spectrometry analysis

Annona muricata extract are extensively used as traditional remedy for a variety of illnesses like cancer, diabetes, hypertension and malaria. Methanol extract of Annona muricata (soursop) stem were analyzed using gas chromatography-mass spectrometry method. The result obtained from the GC-MS analysis of methanol extract of Annona muricata stem led to identification of ten (10) compounds in which 1-(4-hydroxy-6-methyl-2-pyrimidinyl)-2-aziridinone, hexadecanoic acid (palmitic acid) and 9-octadecanoic acid(oleic acid) are the major component reported with significant bioactive impact. The components were identified by comparing their retention indices and mass spectra fragmentation patterns with those stored in the National Institute of Standards and Technology (NIST) library.

Photolytic and thin TiO₂ film assisted photocatalytic degradation of sulfamethazine in aqueous solution.

This paper deals with the photolytic and the photocatalytic degradation of sulfonamide antibiotic sulfamethazine (SMT) dissolved in Milli-Q water and in synthetic wastewater. Besides the direct photolysis, oxidation processes including UV/H2O2, UV/TiO2, and UV/TiO2/H2O2 using UV-A and UV-C radiation were investigated. Pseudo-first-order kinetics was observed for the degradation of SMT in all investigated processes. Additions of an electron acceptor (H2O2) and a catalyst (TiO2 film) accelerated the photolytic degradation of SMT for both the UV-A- and the UV-C-based processes. The most efficient process was UV-C/TiO2/H2O2 with complete degradation of SMT obtained in 10 min. The UV-A-based processes have been less efficient in terms of irradiation time required to totally degrade SMT than the UV-C-based processes. It was also confirmed that different wastewater components can significantly reduce the degradation rate of SMT. An almost ninefold reduction in the rate constant of SMT was observed for the specific synthetic wastewater. Although UV-A radiation experiments need more time and energy (2.7 times more electrical energy was consumed per gram of demineralized SMT) than UV-C experiments, they have a potential for practical use since natural UV-A solar radiation could be used here, which lowers the overall cost of the treatment. Five degradation products were detected during the degradation processes, and their structural formulae are presented. The structural formulae were elucidated based on mass spectra fragmentation pattern obtained using the tandem mass spectrometry (MS/MS) and NMR analysis.

Chemical composition of ethanol extract of Macrotyloma uniflorum (Lam.) Verdc. using GC-MS spectroscopy.

BackgroundMacrotyloma uniflorum Linn (Fabaceae) is a herbaceous plant with annual branches. It is used in kidney stones, inflamed joints, fever, musculoskeletal disorders, sinus wounds and localized abdominal tumors. It is reported as an antioxidant and nutraceutical (forage and food). GC-MS analysis of ethanol extract has led to identification of twenty-eight compounds from M. uniflorum by comparison of their retention indices and mass spectra fragmentation patterns with those stored on the GC-MS computer library.ResultsThe main constituents identified were mome inositol, ethyl alpha-d-glucopyranoside, n- hexadecanoic acid, linoleic acid (9, 12-octadecadienoic acid), its esters and ethyl derivatives, Vitamin E, stigmasterol and 3-beta-stigmast-5-en-3-ol.ConclusionsThe extracts are rich in linoleic acid and its esters, mome inositol and ethyl alpha-d-glucopyranoside; therefore, this plant can be medicinally beneficial as an antioxidant, in diabetes and its related disorders.Electronic supplementary materialThe online version of this article (doi:10.1186/s13588-014-0013-y) contains supplementary material, which is available to authorized users.

Study on Eupatorium triplinerve Vahl from South India, A Rich Source for Thymohydroquinone dimethylether and its Antimicrobial Activity

The seasonal variations, composition and the antimicrobial activity of essential oils from the stem and leaves of Eupatorium triplinerve Vahl were analyzed by gas chromatography-mass spectometry (GC-MS), the components of the essential oils were identified by comparing their mass spectra fragmentation patterns, RI and by the comparison with the literature data. The oil content ranged from 0.25-0.40 %, with comparable in two different seasons. The essential oil obtained from the leaves and the stem was characterized by a very high content of thymohydroquinone dimethylether, i.e. 80.3-86.9 % of the total oil (higher percentage in stem) when compared with the reported values in India (20-40 %). Other oil constituents occurring in much lower amounts were β-caryophyllene (4-6 %), β-eudesmene (6-10 %). The antimicrobial activities of the volatile oil and thymohydroquinone dimethylether were evaluated against four bacterial and four fungal strains using disc diffusion assay method. The stem and leaf essential oils found to have significant antimicrobial effect compared to that of thymohydroquinone dimethylether. Hence the antimicrobial effect of the volatile oil could be attributed to its minor components. The E. triplinerve can be recommended for a new chemotype from south India due to the dominant occurrence of thymohydroquinone dimethylether.

Isotope Cluster-Based Compound Matching in Gas Chromatography/Mass Spectrometry for Non-Targeted Metabolomics

Gas chromatography coupled to mass spectrometry (GC/MS) has emerged as a powerful tool in metabolomics studies. A major bottleneck in current data analysis of GC/MS-based metabolomics studies is compound matching and identification, as current methods generate high rates of false positive and false-negative identifications. This is especially true for data sets containing a high amount of noise. In this work, a novel spectral similarity measure based on the specific fragmentation patterns of electron impact mass spectra is proposed. An important aspect of these algorithmic methods is the handling of noisy data. The performance of the proposed method compared to the dot product, the current gold standard, was evaluated on a complex biological data set. The analysis results showed significant improvements of the proposed method in compound matching and chromatogram alignment compared to the dot product.

Ozonation of triterpenoids: Implications for early diagenesis of biomarkers in oxic environments

This study examines the fate of commonly found organic natural products under exposure to ozone to simulate early oxic diagenesis. The model compounds β-amyrin, lupenone and friedelin have been investigated by ozonation in the presence of water. The transformation products were identified or proposed based on their fragmentation patterns in mass spectra. The double bonds located at the isopropenyl group of lupenone and ring C of β-amyrin are the main reaction sites in the ozonation reaction. The major products identified from the ozonation of β-amyrin are β-amyrone, 12,13-epoxyoleanan-3β-ol, 11-oxo-olean-12-en-3β-ol, 12-oxo-oleanan-3β-ol. In addition, 8,14-seco-12-oxo-olean-14-en-3β-ol, 8,14-seco-12-oxo-olean-13-en-3β-ol and 8,14-seco-oleana-3,12-dione, generated from the bond cleavage between C-8 to C-14 of 12-oxo-oleanan-3β-ol and 12-oxo-oleanan-3-one, respectively, have also been detected. 22,29,30-trisnorlup-18(19)-en-3-one, 22,29,30-trisnorlupan-3-one, 22,29,30-trisnorlupana-3,19-dione, 22,29,30-trisnorlupana-3,12-dione, lupeol, lup-22(29)-en-3-on-29-ol, 22,29-epoxylupan-3-one, lupan-3-on-29-al, lupan-3-on-29-ol and 19,22-epoxylupan-3-one are the major products from the ozonation of lupenone. No transformation product was detected for friedelin, probably due to its stability to ozonation.

CHEMICAL COMPOSITION OF VOLATILE OIL OF OCIMUM SANCTUM LINN.

In traditional systems of medicine, different parts (leaves, stem, flower, root, seeds and even whole plant) of Ocimum sanctum Linn. (known as Tulsi in Hindi), a small herb seen throughout India, have been recommended for the treatment of bronchitis, bronchial asthma, malaria, diarrhea, dysentery, skin diseases, arthritis, painful eye diseases, chronic fever, insect bite etc. The hydro-distilled volatile oil of the O. sanctum leaves was analyzed using GC and GC-MS. The fragmentation patterns of mass spectra were compared with those of the spectrometer data base using NBS 54 AL and Wiley L – built libraries and also with those reported in the literature. Many constituents were identified by comparing their retention indices with those of authentic standards available in author’s laboratory.

Essential Oil Analysis and Antimicrobial Activity of Artemisia parviflora from Losar

The essential oil composition of Artemisia parviflora Buch.-Ham. ex D. Don has been done for the first time from Losar- a Cold Desert of North Indian Higher Altitude Himalayas (4079 m) in July, 2007. Essential oil was isolated by hydro distillation from the aerial parts of the plants collected from the wild sources. The extraction yield for the essential oil of A. parviflora was 0.27 %. The oil was analyzed by GC-MS, the components of the essential oil were identified by comparing their retention indices and mass spectra fragmentation patterns with those stored on the MS-computer library and also from the published literatures. The essential oil analysis led to the identification of 27 constituents representing 80.93 % of the composition of oil. The major constituents of the oil were as following: ß-eudesmol (15.58%), spathulenol (8.50%), ß-selinene (6.0%), citronellol (5.68%), y-cadinene (4.95%), phytol (4.95%), guaiol (4.68%), germacrene-D (3.81%), 10-epi-y-eudesmol (3.51%) and Ot-cadinol (4.51%). The present study describes the phytochemical profile and antimicrobial activity of essential oil of A parviflora. Furthermore, antimicrobial activity of oil was evaluated using agar well diffusion method. The antimicrobial test results showed that the oil had a great potential antimicrobial activity against all 7 bacterial strains. Among all gram positive bacterial growths, the maximum zone of inhibition was recorded against Bacillus subtilis (MTCC-2451), followed by gram negative bacterial strain Salmonella typhimurium (MTCC-1251). The minimum zone of inhibition was recorded against the Escherichia coli (MTCC-443) strain. Among all tested microorganisms, the minimal inhibition concentration (MIC) was recorded in gram negative strain Salmonella typhimurium (MTCC-1251).

Statistical analysis of fragmentation patterns of electron ionization mass spectra of enolized-trimethylsilylated anabolic androgenic steroids

Anabolic androgenic steroids (AAS) are included in the List of prohibited substances of the World Anti-Doping Agency (WADA) as substances abused to enhance athletic performance. Gas chromatography coupled to mass spectrometry (GC–MS) plays an important role in doping control analyses identifying AAS as their enolized-trimethylsilyl (TMS)-derivatives using the electron ionization (EI) mode. This paper explores the suitability of complementary GC–MS mass spectra and statistical analysis (principal component analysis, PCA and partial least squares-discriminant analysis, PLS-DA) to differentiate AAS as a function of their structural and conformational features expressed by their fragment ions. The results obtained showed that the application of PCA yielded a classification among the AAS molecules which became more apparent after applying PLS-DA to the dataset. The application of PLS-DA yielded a clear separation among the AAS molecules which were, thus, classified as: 1-ene-3-keto, 3-hydroxyl with saturated A-ring, 1-ene-3-hydroxyl, 4-ene-3-keto, 1,4-diene-3-keto and 3-keto with saturated A-ring anabolic steroids. The study of this paper also presents structurally diagnostic fragment ions and dissociation routes providing evidence for the presence of unknown AAS or chemically modified molecules known as designer steroids.

Energy-Dependent Kinetic Method: Application to the Multicompetitive Fragmentation Pathways of Protonated Peptides

A variation of the kinetic method for the analysis of fragmentation patterns in mass spectra is proposed. The procedure presents three notable features: no evaluation of the effective temperature of the parent ion is required; the ratio of the activation energies for all competitive channels at play are provided; and the measurement is not biased by the mass discrimination of the instrument. The method is based on the analysis of mass spectra recorded as a function of both the excitation energy and the excitation time. Collision-activated dissociation of protonated Leu-enkephalin achieved in a quadrupolar ion trap and analyzed with this method is presented.

Infrared multiphoton ionization of superhot C60: Experiment and model calculations

We address, both experimentally and theoretically, the issue of infrared (IR) resonance enhanced multiphoton ionization (IR-REMPI) and thermally induced redshifts of IR absorption lines in a very large and highly vibrationally excited molecular system. Isolated superhot C60 molecules with well defined and variable average vibrational energy in the range of 9-19 eV, effusing out of a constant flux thermal source, are excited and ionized after the absorption of multiple (500-800) infrared photons in the 450-1800 cm(-1) spectral energy range. Recording the mass-selected ion signal as a function of IR wavelength gives well resolved IR-REMPI spectra, with zero off-resonance background signal. An enhancement of the ion signal of about a factor of 10 is observed when the temperature is increased from 1200 to 1800 K under otherwise identical conditions. A pronounced temperature dependent redshift of some of the IR absorption lines is observed. The observations are found to be in good agreement with a model which is based on the sequential absorption of single photons, always followed by instantaneous vibrational energy redistribution. The mass spectra (C60(+) fragmentation pattern) are found to be strongly excitation wavelength dependent. Extensive fragmentation down to C32(+) is observed following the absorption of 1350-1400 cm(-1) as well as 1500-1530 cm(-1) photons while negligible fragmentation is observed when exciting around 520 cm(-1).

Isomers among the carbon sulfides C4S6—synthesis and crystal structures of α,α-C4S6, α,β-C4S6, and of a second polymorph of the diiodine adduct α,β-C4S6·I2

The reaction of the alpha and beta forms of C3S5(2-) with thiophosgene yields two isomeric carbon sulfides alpha,alpha-C4S6 and alpha,beta-C4S6, respectively. The crystal structures of both compounds could be determined for the first time. Both structures are made up of almost planar molecules. The alpha,alpha-isomer (1,3-dithiolo-(4,5-d)-1,3-dithol-2,5-dithione) is D2h-symmetric, while the alpha,beta-isomer is approximately Cs-symmetric. In the molecules of both isomers the two different C3S5 units are retained without significant alterations of structural parameters. alpha,alpha-C4S6 is unstable with respect to alpha,beta-C4S6. The molecular rearrangement can be induced by a short thermal treatment at 150 degrees C. Significant differences are found in the mass spectra fragmentation patterns. Only alpha,beta-C4S6 shows an intense signal for C3S2+ and is therefore a potential source for the synthesis of carbon subsulfide via flash vacuum pyrolysis. Only alpha,beta-C4S6 forms a stable adduct with I2. alpha,beta-C4S6.I2 was already known (F. L. Lu, K. M. Keshavarz-K, G. Srdanov, R. H. Jacobson and F. Wudl, J. Org. Chem., 1989, 54, 2165, ), but a second polymorph is formed on crystallisation from a different solvent. The two polymorphic forms do not show differences in the structures of the individual molecules but show a different packing pattern. alpha,beta-C4S6.I2 is remarkably thermally stable. Thermal analysis shows that I2 cleavage occurs in that temperature region above 200 degrees C when C-S bonds are broken and CS2 and I2 are simultaneously liberated. Performed at 270 degrees C thermolysis of alpha,beta-C4S6.I2 yields under cleavage of I2 and CS2 a black polymeric carbon sulfide (CS)x which is probably a mixture of graphitic carbon and unidentified amorphous polymeric carbon sulfides.

Chemotypical Variability of Leaf Oils in Elephantopus scaber from 12 Locations in China

The chemical constituents of leaf oils of Elephantopus scaber L. from 12 locations in Southern China, including three provinces and Hong Kong, were investigated using GC/MS. A total of 24 compounds were detected, of which 20 were identified by their mass spectra fragmentation patterns. The major compounds include hexadecanoic acid (8.19–39.22%), octadecadienoic acid (trace - 29.22%), five alkane homologues, i.e., n-tetradecane (1.19–5.26%), n-pentadecane (3.22–12.05%), n-hexadecane (2.38–16.26%), n-heptadecane (2.48–15.32%), and n-octadecane (1.39–9.59%), as well as tetramethylhexadecenol (2.06–4.31%). Hierarchical cluster analysis classified the leaf oils into two groups. Two main chemotypes of leaf oils in E. scaber were thus identified, one rich in hexadecanoic acid and octadecadienoic acid, and the other rich in the five alkane homologues.

Fragmentation patterns in the electron impact mass spectra of 1,3,5-triazin-2-one derivatives

Fragmentation patterns in the electron impact (EI) mass spectra of a series of 5-substituted 1,3,5- triazin-2-ones, prepared from the reaction of dimethylolurea with selected primary amines, have been elucidated using a combination of high-resolution, comparative low-resolution and metastable peak analysis. In addition to characteristic fragmentations, in which the triazine nucleus remains intact, the 5-substituted 1,3,5-triazin-2-ones appear to exhibit a series of extrusion/ring-contraction processes, resulting in the formation of 3- and 4-membered ring fragments. Resonance-stabilised even-electron ions, arising, in each case, from loss of a hydrogen atom from the molecular ion, are considered pivotal in the formation of these heterocyclic fragments.

Analysis of toxic norditerpenoid alkaloids in Delphinium species by electrospray, atmospheric pressure chemical ionization, and sequential tandem mass spectrometry.

A rapid electrospray mass spectrometry method was developed for screening larkspur (Delphinium spp.) plant material for toxic norditerpenoid alkaloids. The method was calibrated using two standard alkaloids, methyllycaconitine (1) and deltaline (2), with a recovery of 92% from spiked samples and relative standard deviations of 6.0% and 8.1% for the two alkaloids, respectively. Thirty-three samples of plains larkspur, Delphinium geyeri, were analyzed. Methyllycaconitine (1) concentration was 0.27% +/- 0.08% during a 1-month period in 1997 establishing the relative risk of poisoning from the plant to be low. The method was also applied to the trace analysis (<1 ppm) of 1 in serum samples from sheep dosed different levels of the alkaloid. Electrospray ionization combined with sequential tandem mass spectrometry and HPLC coupled to atmospheric pressure chemical ionization (APCI) mass spectrometry were used to detect and tentatively identify three new norditerpenoid alkaloids from Delphinium nuttallianum [bearline (6), 14-acetylbearline (7), 16-deacetylgeyerline (8)]. The tentative structure of the new alkaloids was predicted from the tandem mass spectra fragmentation patterns and assigning the substitution pattern for methoxy and acetyl groups at the C-14 and C-16 carbons.