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https://www.readbyqxmd.com/read/28641225/investigation-of-dissociation-constants-for-individual-and-total-naphthenic-acids-species-using-ultra-performance-liquid-chromatography-ion-mobility-time-of-flight-mass-spectrometry-analysis
#1
Rongfu Huang, Pamela Chelme-Ayala, Yanyan Zhang, Mohamed Changalov, Mohamed Gamal El-Din
Ultra-performance liquid chromatography ion mobility time-of-flight mass spectrometry (UPLC-IM-TOFMS) was utilized for the analysis of naphthenic acids (NAs) in fractions of pH-dependent sequential liquid-liquid extractions from oil sands process-affected water. Ion-mobility separation technique allowed the differentiation of OyS-NAs (2 ≤ y ≤ 4) from Ox-NAs (2 ≤ x ≤ 5) via drift time versus retention time separations. The results indicated that the addition of S atom to the O2-NA molecule led to a lower increase in the dissociation constant (pKa) compared to that caused by the addition of O atom...
June 18, 2017: Chemosphere
https://www.readbyqxmd.com/read/28613826/microtrace-analysis-of-rare-earth-element-residues-in-femtogram-quantities-by-laser-desorption-and-laser-postionization-mass-spectrometry
#2
Zhibin Yin, Zhouyi Xu, Rong Liu, Wei Hang, Benli Huang
A newly developed laser desorption and laser postionization time-of-flight mass spectrometer (LD-LPI-TOFMS) for the direct microtrace determination of rare earth elements (REEs) in residues has been presented. Benefiting from spatially and temporally separated processes between desorption and ionization, LD-LPI-TOFMS plays a dual role in alleviating the barriers of deteriorating spectral resolution at high irradiance, serious matrix effects and elemental fractionation effects at low irradiance. Compared with the conventional laser desorption/ionization (LDI) method, this technique offers unambiguous full-elemental determination of fifteen REEs with more uniform relative sensitivity coefficients (RSCs) ranging from 0...
June 14, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28608392/volatile-organic-compounds-analysis-by-pulsed-glow-discharge-time-of-flight-mass-spectrometry-as-a-structural-elucidation-tool
#3
M Bouza, J Fandino, N Bordel, R Pereiro, A Sanz-Medel
Pulsed glow discharge (PGD) coupled to time of flight mass spectrometry (TOFMS) has been investigated for volatile organic compounds (VOCs) identification and determination. Optimization of PGD operational conditions (chamber design, applied power, pressure and duty cycle) was performed using acetone and benzene as model compounds. During the different optimizations, molecular, fragment and elemental information were obtained when characteristic GD pulse regions were measured. An exploratory study for several VOCs (lineal hydrocarbons, oxygen-containing compounds and aromatic compounds) revealed the capability of the PGD to provide crucial information to elucidate structures (fragments), molecular ions or even proton affinity nature of the molecules; this last information is a consequence of the enriched proton environment generated along the afterglow region for the ionization chamber used...
June 12, 2017: Journal of Mass Spectrometry: JMS
https://www.readbyqxmd.com/read/28601593/detection-of-over-100-selenium-metabolites-in-selenized-yeast-by-liquid-chromatography-electrospray-time-of-flight-mass-spectrometry
#4
Bienvenida Gilbert-López, Mihaly Dernovics, David Moreno-González, Antonio Molina-Díaz, Juan F García-Reyes
The characterization of the selenometabolome of Selenized(Se)-yeast, that is the fraction of water soluble low-molecular weight Se-metabolites produced in Se-yeast is of paramount interest to expand the knowledge on the composition of this food supplement. In this work, we have applied liquid chromatography electrospray time-of-flight mass spectrometry (LC-TOFMS) to search for Se-species from the low molecular weight range fraction of the selenized yeast used for food supplements. Prior to LC-TOFMS, sample treatment consisted of ultrasound assisted water extraction followed by size exclusion fractionation assisted with off-line inductively coupled plasma mass spectrometry detection of isotope (82)Se...
June 4, 2017: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
https://www.readbyqxmd.com/read/28587778/advanced-method-optimization-for-volatile-aroma-profiling-of-beer-using-two-dimensional-gas-chromatography-time-of-flight-mass-spectrometry
#5
Pierre-Hugues Stefanuto, Katelynn A Perrault, Lena M Dubois, Benjamin L'Homme, Catherine Allen, Caitriona Loughnane, Nobuo Ochiai, Jean-François Focant
The complex mixture of volatile organic compounds (VOCs) present in the headspace of Trappist and craft beers was studied to illustrate the efficiency of thermal desorption (TD) comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS) for highlighting subtle differences between highly complex mixtures of VOCs. Headspace solid-phase microextraction (HS-SPME), multiple (and classical) stir bar sorptive extraction (mSBSE), static headspace (SHS), and dynamic headspace (DHS) were compared for the extraction of a set of 21 representative flavor compounds of beer aroma...
June 1, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28582768/investigation-on-the-influence-of-time-of-day-on-benzene-metabolic-pharmacokinetics-by-direct-breath-analysis-in-mice
#6
Yuling Zhang, Wanyang Sun, Dewei Shang, Hao Gao, Zhen Zhou, Xue Li
Benzene, well known as a ubiquitous environmental pollutant, can lead to increasing risk of cancer, bone marrow failure as well as other serious diseases. Benzene has been classified as carcinogenic to humans with no recommended safe level of exposure. In this study, the influence of time-of-day on benzene metabolism has been tentatively explored in a mouse model based on direct real-time breath analysis by using membrane inlet single photon ionization time of flight mass spectrometry (MI-SPI-TOFMS). The exhaled breath of eight mice was monitored at a time resolution of less than 20 s after intraperitoneal (I...
May 23, 2017: Chemosphere
https://www.readbyqxmd.com/read/28566235/investigation-of-storage-time-dependent-alterations-of-enantioselective-amino-acid-profiles-in-kimchi-using-liquid-chromatography-time-of-flight-mass-spectrometry
#7
Moyu Taniguchi, Yutaka Konya, Yosuke Nakano, Eiichiro Fukusaki
Although naturally abundant amino acids are represented mainly by l-enantiomers, fermented foods are known to contain various d-amino acids. Enantiospecific profiles of food products can vary due to fermentation by bacteria, and such alterations may contribute to changes in food properties that would not be dependent exclusively on l-amino acids. Therefore, more attention should be paid to the study of temporal alterations of d-amino acid profiles during fermentation process. However, there have been very few studies reporting time-dependent profiling of d-amino acids because enantioseparation of widely targeted d-amino acids is technically difficult...
May 26, 2017: Journal of Bioscience and Bioengineering
https://www.readbyqxmd.com/read/28544560/fatal-intoxication-by-5f-adb-and-diphenidine-detection-quantification-and-investigation-of-their-main-metabolic-pathways-in-human-by-lc-ms-ms-and-lc-q-tofms
#8
Maiko Kusano, Kei Zaitsua, Kentaro Taki, Kazuaki Hisatsune, Jun'ichi Nakajima, Takako Moriyasu, Tomomi Asano, Yumi Hayashi, Hitoshi Tsuchihashi, Akira Ishii
Despite the implementation of the new blanket scheduling system in 2013, new psychoactive substance (NPS) abuse remains a serious social concern in Japan. We present a fatal intoxication case involving 5F-ADB (methyl 2-[1-(5-fluoropentyl)-1H-indazole-3-carboxamido]-3,3-dimethylbutanoate) and diphenidine. Postmortem blood screening by liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/Q-TOFMS) in the information dependent acquisition (IDA) mode only detected diphenidine. Further urinary screening using an in-house database containing new NPS and metabolites detected not only diphenidine but also possible 5F-ADB metabolites; subsequent targeted screening by LC/tandem mass spectrometry (LC/MS/MS) allowed for the detection of very low level of unchanged 5F-ADB in postmortem heart blood...
May 21, 2017: Drug Testing and Analysis
https://www.readbyqxmd.com/read/28535935/qualitative-analyses-of-less-volatile-organic-molecules-from-female-skin-scents-by-comprehensive-two-dimensional-gas-chromatography-time-of-flight-mass-spectrometry
#9
Petr Doležal, Pavlína Kyjaková, Irena Valterová, Štěpán Urban
Instrumental human scent analysis is undoubtedly desirable for many forensic as well medical applications. Most of the previous human scent studies were focused on volatile organic compounds (VOCs) which were analysed by head space solid phase micro-extraction gas chromatography/mass spectrometry (HS-SPME-GC/MS). This method is, however, significantly less sensitive to "heavier" less volatile compounds emitted from the human skin. These less volatile organic scent molecules probably create the basis of the individual human scent signature, and therefore, our attention is focused mainly on these "heavier" compounds...
May 1, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28535590/emission-of-volatile-organic-compounds-and-production-of-secondary-organic-aerosol-from-stir-frying-spices
#10
Tengyu Liu, Qianyun Liu, Zijun Li, Lei Huo, ManNin Chan, Xue Li, Zhen Zhou, Chak K Chan
Cooking is an important source of volatile organic compounds (VOCs) and a potential source of secondary organic aerosol (SOA) both indoors and outdoors. In this study, VOC emissions from heating corn oil and stir-frying spices (i.e. garlic, ginger, myrcia and zanthoxylum piperitum (Sichuan pepper)) were characterized using an on-line membrane inlet vacuum ultraviolet single-photon ionization time-of-flight mass spectrometer (VUV-SPI-TOFMS). VOC emissions from heating corn oil were dominated by aldehydes, which were enhanced by factors of one order of magnitude when stir-frying spices...
December 1, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28529831/source-identification-of-western-oregon-douglas-fir-wood-cores-using-mass-spectrometry-and-random-forest-classification
#11
Kristen Finch, Edgard Espinoza, F Andrew Jones, Richard Cronn
PREMISE OF THE STUDY: We investigated whether wood metabolite profiles from direct analysis in real time (time-of-flight) mass spectrometry (DART-TOFMS) could be used to determine the geographic origin of Douglas-fir wood cores originating from two regions in western Oregon, USA. METHODS: Three annual ring mass spectra were obtained from 188 adult Douglas-fir trees, and these were analyzed using random forest models to determine whether samples could be classified to geographic origin, growth year, or growth year and geographic origin...
May 2017: Applications in Plant Sciences
https://www.readbyqxmd.com/read/28514513/comprehensive-database-of-manufactured-gas-plant-tars-part-c-heterocyclic-and-hydroxylated-pahs
#12
Christopher Gallacher, Russell Thomas, Richard Lord, Robert M Kalin, Chris Taylor
RATIONALE: Coal tars are a mixture of organic and inorganic compounds and were by-products from the manufactured gas and coke making industries. The tar compositions varied depending on many factors such as the temperature of production and the type of retort used. For this reason a comprehensive database of the compounds found in different tar types is of value to understand both how their compositions differ and what potential chemical hazards are present. This study focuses on the heterocyclic and hydroxylated compounds present in a database produced from 16 different tars from 5 different production processes...
May 17, 2017: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28501191/tlc-uv-hyphenated-with-maldi-tofms-for-the-screening-of-invertase-substrates-in-plant-extracts
#13
Justine Ferey, David Da Silva, Pierre Lafite, Richard Daniellou, Benoît Maunit
In this study, thin-layer chromatography (TLC) hyphenated with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) was developed for the screening of invertase substrates in complex matrices. BfrA, a specific β-D-fructofuranosidase from Leishmania major, was chosen as a model enzyme to screen biological activity in plant extracts due to its capacity to hydrolyze specific carbohydrates. TLC was considered to be a reliable technique for screening substrates (bioactive molecules) in plant extracts due to its quantitative capabilities whereas MALDI-TOFMS was particularly useful for rapid identification...
August 1, 2017: Talanta
https://www.readbyqxmd.com/read/28494122/comprehensive-database-of-manufactured-gas-plant-tars-part-b-aliphatic-and-aromatic-compounds
#14
Christopher Gallacher, Russell Thomas, Richard Lord, Robert M Kalin, Chris Taylor
RATIONALE: Coal tars are a mixture of organic and inorganic compounds and were produced as a by-product from the manufactured gas and coke making industries. The composition of the tar produced varied depending on many factors; these include the temperature of production and the type of retort used. As different production processes produce different tars, a comprehensive database of the compounds present within coal tars from different production processes is a valuable resource. Such a database would help to understand how their chemical properties differ and what hazards the compounds present within these tars might pose...
May 11, 2017: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28488792/comprehensive-database-of-manufactured-gas-plant-tars-part-a-database
#15
Christopher Gallacher, Russell Thomas, Richard Lord, Robert M Kalin, Chris Taylor
RATIONALE: Coal tars are a mixture of organic and inorganic compounds and were by-products from the manufactured gas and coke making industries. Different manufacturing processes have resulted in the production of distinctly different tar compositions. This study presents a comprehensive database of compounds produced using two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GCxGC/TOFMS), analysing 16 tar samples produced by 5 distinct production processes...
May 10, 2017: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28473200/thermal-desorption-comprehensive-two-dimensional-gas-chromatography-coupled-to-variable-energy-electron-ionization-time-of-flight-mass-spectrometry-for-monitoring-subtle-changes-in-volatile-organic-compound-profiles-of-human-blood
#16
Lena M Dubois, Katelynn A Perrault, Pierre-Hugues Stefanuto, Stefan Koschinski, Matthew Edwards, Laura McGregor, Jean-François Focant
Blood is a matrix with high potential for forensic investigations and human rescue. Its volatile signature can be used in search exercises to locate injured or deceased individuals. Little is known, however, about the volatile organic compound (VOC) profile of blood, except that it is complex and varies while blood ages. In the present study, we used thermal desorption (TD) and comprehensive two-dimensional gas chromatography (GCxGC) coupled to variable-energy electron ionization time-of-flight mass spectrometry (TOFMS) to monitor VOC signatures of human blood...
April 13, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28452071/oxidative-stress-in-asthmatic-and-non-asthmatic-adolescent-swimmers-a-breathomics-approach
#17
Mariana Couto, Corália Barbosa, Diana Silva, Alisa Rudnitskaya, Luís Delgado, André Moreira, Sílvia M Rocha
We hypothesize that oxidative stress induced by trichloramine exposure during swimming could be related to etiopathogenesis of asthma among elite swimmers. AIM: To investigate the effect of a swimming training session on oxidative stress markers of asthmatic compared to non-asthmatic elite swimmers using exhaled breath (EB) metabolomics. METHODS: Elite swimmers annually screened in our department (n=27) were invited and those who agreed to participate (n=20, of which 9 with asthma) had EB collected (Tedlar(®) bags) before and after a swimming training session...
April 27, 2017: Pediatric Allergy and Immunology
https://www.readbyqxmd.com/read/28437060/high-throughput-and-quantitative-measurement-of-microbial-metabolome-by-gas-chromatography-mass-spectrometry-using-automated-alkyl-chloroformate-derivatization
#18
Linjing Zhao, Yan Ni, Mingming Su, Hongsen Li, Fangcong Dong, Wenlian Chen, Runmin Wei, Lulu Zhang, Seu Ping Guiraud, Francois-Pierre Martin, Cynthia Rajani, Guoxiang Xie, Wei Jia
The ability to identify and quantify small molecule metabolites derived from gut microbial-mammalian cometabolism is essential for the understanding of the distinct metabolic functions of the microbiome. To date, analytical protocols that quantitatively measure a complete panel of microbial metabolites in biological samples have not been established but are urgently needed by the microbiome research community. Here, we report an automated high-throughput quantitative method using a gas chromatography/time-of-flight mass spectrometry (GC/TOFMS) platform to simultaneously measure over one hundred microbial metabolites in human serum, urine, feces, and Escherichia coli cell samples within 15 min per sample...
May 2, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28436032/application-of-maldi-tof-ms-for-estimating-the-postmortem-interval-in-rat-muscle-samples
#19
Chengzhi Li, Dong Ma, Kaifei Deng, Yijiu Chen, Ping Huang, Zhenyuan Wang
Estimating the postmortem interval (PMI) is very important in the forensic sciences. Although many approaches have been used for estimating the PMI, accurate PMI calculations are still difficult. In this study, four Sprague Dawley (SD) rats were sacrificed by suffocation, and muscle samples were collected by dissection at various time intervals (0, 48, 96, and 144 h) after death. All samples were probed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) to obtain molecular images and data for principal component analysis (PCA)...
April 23, 2017: Journal of Forensic Sciences
https://www.readbyqxmd.com/read/28424429/the-volatile-molecule-signature-of-four-mycobacteria-species
#20
Theodore Mellors, Christiaan Rees, Wendy Wieland-Alter, C Fordham von Reyn, Jane E Hill
Mycobacteria are the leading cause of death from infectious disease worldwide and limitations in current diagnostics are hampering control efforts. In recent years, the use of small volatile molecules as diagnostic biomarkers for mycobacteria has shown promise for use in the rapid analysis of in vitro cultures as well as ex vivo diagnosis using breath or sputum. In this study, 18 strains from four mycobacteria species (Mycobacterium avium, M. bovis BCG, M. intracellulare and M. xenopi) were analyzed for the first time using two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS)...
April 20, 2017: Journal of Breath Research
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