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Mass Data (mass + data)
Kinds of Mass Data Selected AbstractsDifferentiation of structural isomers in a target drug database by LC/Q-TOFMS using fragmentation predictionDRUG TESTING AND ANALYSIS, Issue 6 2010Elli Tyrkkö Abstract Isomers cannot be differentiated from each other solely based on accurate mass measurement of the compound. A liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/Q-TOFMS) method was used to systematically fragment a large group of different isomers. Two software programs were used to characterize in silico mass fragmentation of compounds in order to identify characteristic fragments. The software programs employed were ACD/MS Fragmenter (ACD Labs Toronto, Canada), which uses general fragmentation rules to generate fragments based on the structure of a compound, and SmartFormula3D (Bruker Daltonics), which assigns fragments from a mass spectra and calculates the molecular formulae for the ions using accurate mass data. From an in-house toxicology database of 874 drug substances, 48 isomer groups comprising 111 compounds, for which a reference standard was available, were found. The product ion spectra were processed with the two software programs and 1,3 fragments were identified for each compound. In 82% of the cases, the fragment could be identified with both software programs. Only 10 isomer pairs could not be differentiated from each other based on their fragments. These compounds were either diastereomers or position isomers undergoing identical fragmentation. Accurate mass data could be utilized with both software programs for structural elucidation of the fragments. Mean mass accuracy and isotopic pattern match values (SigmaFit; Bruker Daltonics Bremen, Germany) were 0.9 mDa and 24.6 mSigma, respectively. The study introduces a practical approach for preliminary compound identification in a large target database by LC/Q-TOFMS without necessarily possessing reference standards. Copyright © 2010 John Wiley & Sons, Ltd. [source] Burning and dripping behaviors of polymers under the UL94 vertical burning test conditionsFIRE AND MATERIALS, Issue 4 2010Yong Wang Abstract An experimental setup was constructed to record the real-time mass data of eight pure polymers under the UL94 vertical burning test conditions. The experiments showed that the flame rises up to the clamp or the dripping occurs soon for the pure polymers. The mass burned before the flame reaching the clamp and the dripping occurrence only accounts for a small fraction of the original mass of the specimen, which differentiates the UL94 test from the cone calorimeter test. The mass loss rate of polymer specimens is in the magnitude order of 0.001,0.01,g/s. It was also found that the flame of thin specimens usually reaches the clamp sooner than that of thick specimens. Apart from the dripping behaviors found in large-scale fires, it is found that the diameter of the first drop for the tested polymers is in the range of 2.0,10.0,mm. The mass of the first drop increases with the first dripping time. The first dripping time and the mass of the first drop increase with the thickness of the specimen, especially for polymers of large-size dripping type. Copyright © 2009 John Wiley & Sons, Ltd. [source] Does size matter for dispersal distance?GLOBAL ECOLOGY, Issue 4 2007David G. Jenkins ABSTRACT Aim, The aim of this study is to answer the questions: (1) do small organisms disperse farther than large, or vice versa; and (2) does the observed pattern differ for passive and active dispersers? These questions are central to several themes in biogeography (including microbial biogeography), macroecology, metacommunity ecology and conservation biology. Location, The meta-analysis was conducted using published data collected worldwide. Methods, We collected and analysed 795 data values in the peer-reviewed literature for direct observations of both maximal dispersal distance and mass of the dispersing organisms (e.g. seeds, not trees). Analysed taxa ranged in size from bacteria to whales. We applied macroecology analyses based on null models (using Monte Carlo randomizations) to test patterns relative to specific hypotheses. Results, Collected dispersal distance and mass data spanned 9 and 21 orders of magnitude, respectively. Active dispersers dispersed significantly farther (P < 0.001) and were significantly greater in mass (P < 0.001) than passive dispersers. Overall, size matters: larger active dispersers attained greater maximum observed dispersal distances than smaller active dispersers. In contrast, passive-disperser distances were random with respect to propagule mass, but not uniformly random, in part due to sparse data available for tiny propagules. Conclusions, Size is important to maximal dispersal distance for active dispersers, but not for passive dispersers. Claims that microbes disperse widely cannot be tested by current data based on direct observations of dispersal: indirect approaches will need to be applied. Distance,mass relationships should contribute to a resolution of neutral and niche-based metacommunity theories by helping scale expectations for dispersal limitation. Also, distance,mass relationships should inform analyses of latitudinal species richness and conservation biology topics such as fragmentation, umbrella species and taxonomic homogenization. [source] When and where to fuel before crossing the Sahara desert , extended stopover and migratory fuelling in first-year garden warblers Sylvia borinJOURNAL OF AVIAN BIOLOGY, Issue 2 2008Thord Fransson Large numbers of passerine migrants cross the Sahara desert every year on their way to-and-from wintering areas in tropical Africa. In the desert, hardly any fuelling opportunities exist and most migrants have to prepare in advance. A central question is how inexperienced birds know where to fuel. Inexperienced garden warblers Sylvia borin were studied in Greece just before the desert crossing in autumn. Body mass data collected at two sites indicate that most birds do not fuel for the desert crossing further north. For the first time, detailed information about stopover duration close to the Sahara desert was studied by using light weight radio-transmitters. Results from Crete show that most first-year garden warblers arrive with relatively small fuel loads in relation to lean body mass (<30%), stay for 13,20 d and depart with an average fuel load of about 100%. Radio-tagged birds performed small scale movements initially and took advantage of fig fruits. Birds trapped at fig trees were heavier than birds trapped with tape lures, showing that tape lures can bias the sample of migrants trapped. The precise fuelling pattern found indicates that first-year migrants must also include external spatial cues to make the preparation for crossing the desert in the right area. [source] An allometric function to fit leg-loop harnesses to terrestrial birdsJOURNAL OF AVIAN BIOLOGY, Issue 3 2007Beat Naef-Daenzer Harnesses are indispensable for a long-term attachment of instruments to animals, particularly birds. The exact fit is crucial for both the reliability of the tags and the animals' health and natural behaviour. Using data from 19 bird species ranging from 8,400 g, I present an allometric function to calculate the dimension of leg-loop harnesses for birds on the basis of body mass data. The model greatly facilitates determining the correct loop span for new species without time-consuming experiments. More importantly, the equation permits calculation of the excess span that is required for tagging juvenile, still growing birds. [source] A multivariate approach to the feeding habits of small fishes in the Guadalquivir EstuaryJOURNAL OF FISH BIOLOGY, Issue 2002F. Baldoa In the analysis of the feeding habits of the 11 most abundant fish species in the Guadalquivir Estuary, collected monthly (February 1998 to January 1999) at two different sampling sites, a total of 46 prey taxa were identified. Classifications (based on Bray,Curtis similarities derived from occurrence, number and mass data) of the different fish categories (postlarvae and juvenile,adults of each species) revealed two main trophic guilds, whose preferential prey (SIMPER analysis) were mysids and copepods, respectively. The similarity matrices derived from occurrence, number and mass data were always significantly correlated (RELATE: r>0.636; P<0.01), indicating that a good agreement in feeding patterns emerged from these variables. The seasonal coincidence of maximal fish and key-prey species densities suggests that food availability may be a principal factor influencing the nursery function of the Guadalquivir Estuary. [source] Searching for anthropogenic contaminants in human breast adipose tissues using gas chromatography-time-of-flight mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 1 2009Félix Hernández Abstract The potential of gas chromatography-time-of-flight mass spectrometry (GC-TOF MS) for screening anthropogenic organic contaminants in human breast adipose tissues has been investigated. Initially a target screening was performed for a list of 125 compounds which included persistent halogen pollutants [organochlorine (OC) pesticides, polychlorinated biphenylss (PCBs), polybrominated diphenyl ethers (PBDEs)], polyaromatic hydrocarbons (PAHs), alkylphenols, and a notable number of pesticides from the different fungicide, herbicide and insecticide families. Searching for target pollutants was done by evaluating the presence of up to five representative ions for every analyte, all measured at accurate mass (20-mDa mass window). The experimental ion abundance ratios were then compared to those of reference standards for confirmation. Sample treatment consisted of an extraction with hexane and subsequent normal-phase (NP) High performance liquid chromatography (HPLC) or SPE cleanup. The fat-free LC fractions were then investigated by GC-TOF MS. Full-spectral acquisition and accurate mass data generated by GC-TOF MS also allowed the investigation of nontarget compounds using appropriate processing software to manage MS data. Identification was initially based on library fit using commercial nominal mass libraries. This was followed by comparing the experimental accurate masses of the most relevant ions with the theoretical exact masses with calculations made using the elemental composition calculator included in the software. The application of both target and nontarget approaches to around 40 real samples allowed the detection and confirmation of several target pollutants including p,p,-DDE, hexachlorobenzene (HCB), and some polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). Several nontarget compounds that could be considered anthropogenic pollutants were also detected. These included 3,5-di- tert -butyl-4-hydroxy-toluene (BHT) and its metabolite 3,5-di- tert -butyl-4-hydroxybenzaldehyde (BHT-CHO), dibenzylamine, N -butyl benzenesulfonamide (N -BBSA), some naphthalene-related compounds and several PCBs isomers not included in the target list. As some of the compounds detected are xenoestrogens, the methodology developed in this paper could be useful in human breast cancer research. Copyright © 2008 John Wiley & Sons, Ltd. [source] Mass spectrometric analysis of the marine lipophilic biotoxins pectenotoxin-2 and okadaic acid by four different types of mass spectrometersJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 8 2008Arjen Gerssen Abstract The performances of four different mass spectrometers [triple-quadrupole (TQ), time-of-flight (ToF), quadrupole ToF (Q-ToF) and ion trap (IT)] for the detection of the marine lipophilic toxins pectenotoxin-2 (PTX2) and okadaic acid (OA) were investigated. The spectral data obtained with the different mass spectrometric analyzers were used to propose fragmentation schemes for PTX2 in the positive electrospray mode and for OA in the negative electrospray mode. TQ data were used to obtain product ions, while ToF and Q-ToF-MS produced accurate mass data of the precursor ion and product ions, respectively. IT data provided a better understanding of the fragmentation pathways using MSn experiments. With respect to analytical performance, all four mass analyzers showed a good linearity (R2 > 0.97) and repeatability (CV < 20%). Detection limits (LoDs) (S/N = 3) were the lowest on triple-quad MS: 12.2 and 2.9 pg on-column for PTX2 and OA, respectively. Copyright © 2008 John Wiley & Sons, Ltd. [source] Collision-induced dissociation of sulfur-containing imidazolium ionic liquidsJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 1 2008Alain Lesimple Abstract A number of 1,2-dimethylimidazole ionic liquids substituted on NII with alkyl chains of varying lengths terminated with sulfur-containing groups were investigated by electrospray high-resolution tandem Fourier-transform mass spectrometry. Fragmentation pathways are strongly dependent on the oxidation state of the sulfur and the alkyl chain length. The dissociations detected are rationalized by deuterium labeling, comparisons between homologous compounds and accurate mass data. Several homolytic processes are reported, leading to distonic ions and loss of hydrogen, methyl and other free radicals. Copyright © 2007 John Wiley & Sons, Ltd. [source] Effect of density homogeneity on the dynamic response of powder bedsAICHE JOURNAL, Issue 8 2003T. Yanagida Homogeneous and inhomogeneous powder beds subjected to low-magnitude vibration are compared in terms of the dynamic response. The inhomogeneous samples were segregated into two phases: loose and dense phases, layering the two phases horizontally or vertically. An apparent mass, defined as a ratio of the base force to base acceleration, was measured. Comparison of homogeneous and segregated data demonstrated a significant density gradient dependence on the apparent mass data. First, homogeneous systems showed a resonant peak, which gave the longitudinal elastic modulus of the bed via the velocity of longitudinal stress wave propagation. Second, vertically segregated systems exhibited two significant peaks at low frequencies, corresponding to the resonance of each phase. In addition, the apparent mass values at the two peaks were related to the quantity of each phase. Third, horizontally segregated systems exhibited a resonant peak, whose frequency was approximately equal to homogeneous data, but the apparent mass value at the peak differed from homogeneous data. A model based on the fourth-power scaling law, two-phase theory and Rayleigh's energy method gave an interpretation for the insensitivity of the peak frequency to the density gradient in the vertical direction. [source] Simultaneous qualification and quantification of eight triterpenoids in Radix Achyranthis Bidentatae by high-performance liquid chromatography with evaporative light scattering detection and mass spectrometric detectionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 6 2007Juan Li Abstract An HPLC with evaporative light scattering detection (ELSD) and ESI-MS was established for the simultaneous determination of eight triterpenoids in Radix Achyranthis Bidentatae. The optimal chromatographic conditions were achieved on a Zorbax C18 column by linear gradient elution with 0.08% v/v aqueous formic acid and ACN as the mobile phase at the flow rate of 0.8 mL/min. Temperature for the detector drift tube was set at 101°C and the nitrogen flow rate was 2.8 L/min. The identities of the analytes were accomplished by comparing retention times and mass data with those of reference compounds. The validation of the method included tests of linearity, sensitivity, repeatability, recovery, and stability. All the calibration curves of the eight triterpenoids showed good linear regression (R2 >0.997) within the test ranges. The method provides desirable repeatability with overall intra- and interday variations of less than 4.9%. The obtained recoveries varied between 93.6 and 98.1% while the RSDs were below 3.9% (n = 3). The analysis results indicate that the content of investigated triterpenoids in Radix Achyranthis Bidentatae from different locations was greatly diverse, and the triterpenoids could be used as chemical markers for the discrimination of genuine and ungenuine crude drugs. [source] Improved detection of reactive metabolites with a bromine-containing glutathione analog using mass defect and isotope pattern matchingRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 9 2010André LeBlanc Drug bioactivation leading to the formation of reactive species capable of covalent binding to proteins represents an important cause of drug-induced toxicity. Reactive metabolite detection using invitro microsomal incubations is a crucial step in assessing potential toxicity of pharmaceutical compounds. The most common method for screening the formation of these unstable, electrophilic species is by trapping them with glutathione (GSH) followed by liquid chromatography/mass spectrometry (LC/MS) analysis. The present work describes the use of a brominated analog of glutathione, N -(2-bromocarbobenzyloxy)-GSH (GSH-Br), for the invitro screening of reactive metabolites by LC/MS. This novel trapping agent was tested with four drug compounds known to form reactive metabolites, acetaminophen, fipexide, trimethoprim and clozapine. Invitro rat microsomal incubations were performed with GSH and GSH-Br for each drug with subsequent analysis by liquid chromatography/high-resolution mass spectrometry on an electrospray time-of-flight (ESI-TOF) instrument. A generic LC/MS method was used for data acquisition, followed by drug-specific processing of accurate mass data based on mass defect filtering and isotope pattern matching. GSH and GSH-Br incubations were compared to control samples using differential analysis (Mass Profiler) software to identify adducts formed via the formation of reactive metabolites. In all four cases, GSH-Br yielded improved results, with a decreased false positive rate, increased sensitivity and new adducts being identified in contrast to GSH alone. The combination of using this novel trapping agent with powerful processing routines for filtering accurate mass data and differential analysis represents a very reliable method for the identification of reactive metabolites formed in microsomal incubations. Copyright © 2010 John Wiley & Sons, Ltd. [source] Comparison of triple quadrupole, hybrid linear ion trap triple quadrupole, time-of-flight and LTQ-Orbitrap mass spectrometers in drug discovery phase metabolite screening and identification in vitro , amitriptyline and verapamil as model compoundsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2010Timo Rousu Liquid chromatography in combination with mass spectrometry (LC/MS) is a superior analytical technique for metabolite profiling and identification studies performed in drug discovery and development laboratories. In the early phase of drug discovery the analytical approach should be both time- and cost-effective, thus providing as much data as possible with only one visit to the laboratory, without the need for further experiments. Recent developments in mass spectrometers have created a situation where many different mass spectrometers are available for the task, each with their specific strengths and drawbacks. We compared the metabolite screening properties of four main types of mass spectrometers used in analytical laboratories, considering both the ability to detect the metabolites and provide structural information, as well as the issues related to time consumption in laboratory and thereafter in data processing. Human liver microsomal incubations with amitriptyline and verapamil were used as test samples, and early-phase ,one lab visit only' approaches were used with all instruments. In total, 28 amitriptyline and 69 verapamil metabolites were found and tentatively identified. Time-of-flight mass spectrometry (TOFMS) was the only approach detecting all of them, shown to be the most suitable instrument for elucidating as comprehensive metabolite profile as possible leading also to lowest overall time consumption together with the LTQ-Orbitrap approach. The latter however suffered from lower detection sensitivity and false negatives, and due to slow data acquisition rate required slower chromatography. Approaches with triple quadrupole mass spectrometry (QqQ) and hybrid linear ion trap triple quadrupole mass spectrometry (Q-Trap) provided the highest amount of fragment ion data for structural elucidation, but, in addition to being unable to produce very high-important accurate mass data, they suffered from many false negatives, and especially with the QqQ, from very high overall time consumption. Copyright © 2010 John Wiley & Sons, Ltd. [source] Metabolite identification of small interfering RNA duplex by high-resolution accurate mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2008Yan Zou On-line liquid chromatography/electrospray ionization high-resolution mass spectrometry (LC/ESI-HRMS) using an LTQ-Orbitrap mass spectrometer was employed to investigate the metabolite profiles of a model siRNA duplex designated HBV263. The HBV263 duplex was incubated in rat and human serum and liver microsomes in vitro. The siRNA drug and its metabolites were then extracted using a liquid-liquid extraction followed by solid-phase extraction (LLE-SPE), and analyzed by LC/ESI-MS. High-resolution accurate mass data enabled differentiation between two possible metabolite sequences with a monoisotopic molecular mass difference of less than 1,Da. ProMass deconvolution software was used to provide semi-automated data processing. In vitro serum and liver microsome incubation samples afforded different metabolite patterns: the antisense strand of the duplex was degraded preferentially in rat and human serum, while the sense strand of the duplex was less stable in rat and human liver microsomes. Copyright © 2008 John Wiley & Sons, Ltd. [source] Studies on azaspiracid biotoxins.RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 24 2002In this report, the mass spectral analysis of azaspiracid biotoxins is described. Specifically, the collision-induced dissociation (CID) behavior and differences between CID spectra obtained on a triple-quadrupole, a quadrupole time-of-flight, and an ion-trap mass spectrometer are addressed here. The CID spectra obtained on the triple-quadrupole mass spectrometer allowed the classification of the major product ions of the five investigated compounds (AZA 1,5) into five distinct fragment ion groups, according to the backbone cleavage positions. Although the identification of unknown azaspiracids was difficult based on CID alone, the spectra provided sufficient structural information to allow confirmation of known azaspiracids in marine samples. Furthermore, we were able to detect two new azaspiracid analogs (AZA 1b and 6) in our samples and provide a preliminary structural analysis. The proposed dissociation pathways under tandem mass spectrometry (MS/MS) conditions were confirmed by a comparison with accurate mass data from electrospray quadrupole time-of-flight MS/MS experiments. Regular sequential MSn analysis on an ion-trap mass spectrometer was more restricted in comparison to the triple-quadrupole mass spectrometer, because the azaspiracids underwent multiple [M,+,H,,,nH2O]+ (n,=,1,6) losses from the precursor ion under CID. Thus, the structural information obtained from MSn experiments was somewhat limited. To overcome this limitation, we developed a wide-range excitation technique using a 180-u window that provided results comparable to the triple-quadrupole instrument. To demonstrate the potential of the method, we applied it to the analysis of degraded azaspiracids from mussel tissue extracts. Copyright © 2002 John Wiley & Sons, Ltd. [source] Allometry of facial mobility in anthropoid primates: Implications for the evolution of facial expressionAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2009Seth D. Dobson Abstract Body size may be an important factor influencing the evolution of facial expression in anthropoid primates due to allometric constraints on the perception of facial movements. Given this hypothesis, I tested the prediction that observed facial mobility is positively correlated with body size in a comparative sample of nonhuman anthropoids. Facial mobility, or the variety of facial movements a species can produce, was estimated using a novel application of the Facial Action Coding System (FACS). I used FACS to estimate facial mobility in 12 nonhuman anthropoid species, based on video recordings of facial activity in zoo animals. Body mass data were taken from the literature. I used phylogenetic generalized least squares (PGLS) to perform a multiple regression analysis with facial mobility as the dependent variable and two independent variables: log body mass and dummy-coded infraorder. Together, body mass and infraorder explain 92% of the variance in facial mobility. However, the partial effect of body mass is much stronger than for infraorder. The results of my study suggest that allometry is an important constraint on the evolution of facial mobility, which may limit the complexity of facial expression in smaller species. More work is needed to clarify the perceptual bases of this allometric pattern. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source] On-Line HPLC-UV-mass spectrometry and tandem mass spectrometry for the rapid delineation and characterization of differences in complex mixtures: a case study using toxic oil variantsBIOMEDICAL CHROMATOGRAPHY, Issue 5 2002Frank W. Crow An integrated differential approach to the characterization of complex mixtures is presented which includes the targeting of liquid chromatography (LC) peaks for identification using characteristic UV adsorption of the LC peak, subsequent molecular weight and formula determination using accurate mass LC mass spectrometry (MS), and structure characterization using accurate mass LC-tandem mass spectrometry. The use of differential UV adsorption aids in narrowing the scope of the study to only specific peaks of interest. Accurate mass measurement of the molecular ion species provides molecular weight information as well as atomic composition information. The tandem MS (MS/MS) spectra provide fragmentation information which allows for structural characterization of each component. Accurate mass assignment of each of the fragment ions in the MS/MS spectrum provides atomic composition for each of the fragment ions and thus further aids in the structural characterization. These experiments are facilitated through the use of on-line LC-MS and LC-MS/MS with in-line UV detection. A synthetic toxic oil (STO) related to Toxic Oil Syndrome is studied with a focus on possible contaminants resulting from the interaction of aniline, used as a denaturant, with the normal components of the oil. A differential analysis between the STO and a control oil is performed. LC peaks were targeted using UV absorbance to indicate the possible presence of the aniline moiety. Further differential analysis was performed through the determination of the MS signals associated with each component separated on the LC. Finally, the MS/MS data was also used to determine if the fragmentation of the targeted components indicated the presence of aniline. The MS/MS and accurate mass data were used to assign the structures for the targeted components. Copyright © 2002 John Wiley & Sons, Ltd. [source] Normative dual energy X-ray absorptiometry data in Swedish children and adolescentsACTA PAEDIATRICA, Issue 7 2010Gayani Alwis Abstract Aim:, To present normative dual energy X-ray absorptiometry data in healthy young Swedes. Methods:, Included were 710 girls and 759 boys aged 6,30 years from southern Sweden. Bone mineral content, bone mineral density, bone size, lean body and fat mass were measured by dual energy X-ray absorptiometry in total body, lumbar spine, hip, arms and legs. Results:, Swedish children had similar bone mass to children in the Netherlands but higher than children in Canada and Korea. Height, weight, bone mass, bone size and lean mass increased at a constant rate from age 6 until the rapid increase in all traits at puberty. The pubertal growth spurt started earlier in girls than in boys, while the spurt in boys was larger in magnitude and occurred for a longer period. Around one-quarter of the adult total body and lumbar spine peak bone mineral content was gained during the 2 years with the fastest gain in both genders. Conclusion:, This study presents normative bone mass data in Swedish children, data that are similar to that in Dutch children but higher than in Canadian and Korean children. The gain in Swedish children seems to mimic the gain seen in children in other settings. [source] Fragmentation Mechanism of Trans -,-Aryl-,-enamino EstersCHINESE JOURNAL OF CHEMISTRY, Issue 8 2002Nan Jiang Abstract Electron impact-induced fragmentation mechanisms of trans-, -aryl- , -enamino esters were investigated using mass-analyzed ion kinetic energy (MIKE) spectrometry and high resolution accurate mass data. It was found that the main characteristic fragmentations of compounds studied were: an odd electron ion M+ - EtOH was formed by losing a neutral molecule of ethanol; and the skeletal rearrangements took place; and the ring opening reaction happened after losing a carbon monoxide; and the typical McLafferty rearrangement underwent in ester group. The cyclization reaction caused by losing neutral molecule of TsNH2 due to the ortho -effects of substituted group of aromatic ring was also observed. [source] | ||||||||||||||||