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Ambient ionization

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https://www.readbyqxmd.com/read/29766603/characterization-of-aerosol-nitroaromatic-compounds-validation-of-an-experimental-method
#1
Mohammed Jaoui, Michael Lewandowski, John H Offenberg, Maribel Colon, Kenneth S Docherty, Tadeusz E Kleindienst
The analytical capabilities associated with the use of silylation reactions have been extended to a new class of organic molecules, nitroaromatic compounds (NACs). These compounds are a possible contributor to urban particulate matter of secondary origin which would make them important analytes due to their (1) detrimental health effects, (2) potential to affect aerosol optical properties, (3) and usefulness for identifying PM2.5 from biomass burning. The technique is based on derivatization of the parent NACs using N,O-bis-(trimethylsilyl)-trifluoro acetamide, one of the most prevalent derivatization reagent for analyzing hydroxylated molecules, followed by GC-MS using electron ionization (EI) and methane chemical ionization (CI)...
May 15, 2018: Journal of Mass Spectrometry: JMS
https://www.readbyqxmd.com/read/29765695/influence-of-high-altitude-on-the-burning-behaviour-of-typical-combustibles-and-the-related-responses-of-smoke-detectors-in-compartments
#2
Ran Tu, Yi Zeng, Jun Fang, Yong-Ming Zhang
The effect of altitude on typical combustible burning and related smoke detector response signals was investigated by comparison experiments at altitudes of 40 m and 3650 m based on EN54 standard tests. Point-type light scattering photoelectric smoke detectors and ionization smoke detectors were used for four kinds of EN54 fire tests, including two kinds of smouldering fires with wood (test fire no. 2 in EN54 standard or TF2) and cotton (TF3), and two kinds of flaming fires with polyurethane (TF4) and n -heptane (TF5)...
April 2018: Royal Society Open Science
https://www.readbyqxmd.com/read/29759207/in-vivo-monitoring-of-nicotine-biosynthesis-in-tobacco-leaves-by-low-temperature-plasma-mass-spectrometry
#3
Sandra Martínez-Jarquín, Humberto Herrera-Ubaldo, Stefan de Folter, Robert Winkler
Low-temperature plasma (LTP) is capable of ionizing a broad range of organic molecules at ambient conditions. The coupling of LTP to a mass analyzer delivers chemical profiles from delicate objects. To investigate the suitability of LTP ionization for mass spectrometry (MS) based in vivo studies, we monitored the auxin-regulated nicotine biosynthesis in tobacco (Nicotiana tabacum) and evaluated possible biological effects. The measured nicotine concentrations in different experiments were comparable to literature data obtained with conventional methods...
August 1, 2018: Talanta
https://www.readbyqxmd.com/read/29754610/thread-spray-mass-spectrometry-for-direct-analysis-of-capsaicinoids-in-pepper-products
#4
Sierra Jackson, Devin J Swiner, Patricia C Capone, Abraham K Badu-Tawiah
Thread spray ambient ionization uses single threads as a medium for sampling and ionization. This approach was demonstrated through the detection of various capsaicinoids from the interior of pepper fruits without destruction of the sample. Pepper residues present on the thread were analyzed by the application of DC voltage and solvent to cause field-induced charged droplet generation. Capsaicinoids extracted from the sample are contained in the electrosprayed droplets and transported to the mass spectrometer for characterization...
September 6, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29753153/efficient-derivatization-of-methylphosphonic-and-aminoethylsulfonic-acids-related-to-nerve-agents-simultaneously-in-soils-using-trimethyloxonium-tetrafluoroborate-for-their-enhanced-qualitative-detection-and-identification-by-ei-gc-ms-and-gc-fpd
#5
Carlos A Valdez, Mira K Marchioretto, Roald N Leif, Saphon Hok
Trimethyloxonium tetrafluoroborate (TMO·BF4 ) has been used in the simultaneous derivatization of phosphonic and 2-aminoethylsulfonic acids related to nerve agents in different soils for their enhanced detection and identification by electron ionization gas chromatography-mass spectrometry (EI-GC-MS). The panel of acids consisted of five Schedule 2 phosphonic acids (methyl methylphosphonic acid, ethyl methylphosphonic acid, isopropyl methylphosphonic acid, pinacolyl methylphosphonic acid and cyclohexyl methylphosphonic acid) along with two sulfonic acids, N,N-diethyl-2-aminoethylsulfonic acid and N,N-diisopropyl-2-aminoethylsulfonic acid...
April 27, 2018: Forensic Science International
https://www.readbyqxmd.com/read/29725476/radiofrequency-radiation-from-nearby-base-stations-gives-high-levels-in-an-apartment-in-stockholm-sweden-a-case-report
#6
Lennart Hardell, Michael Carlberg, Lena K Hedendahl
Exposure to radiofrequency (RF) radiation was classified in 2011 as a possible human carcinogen, Group 2B, by the International Agency for Research on Cancer of the World Health Organisation. Evidence of the risk of cancer risk has since strengthened. Exposure is changing due to the rapid development of technology resulting in increased ambient radiation. RF radiation of sufficient intensity heats tissues, but the energy is insufficient to cause ionization, hence it is called non-ionizing radiation. These non-thermal exposure levels have resulted in biological effects in humans, animals and cells, including an increased cancer risk...
May 2018: Oncology Letters
https://www.readbyqxmd.com/read/29718662/high-spatial-resolution-imaging-of-mouse-pancreatic-islets-using-nanospray-desorption-electrospray-ionization-mass-spectrometry
#7
Ruichuan Yin, Jennifer E Kyle, Kristin E Burnum-Johnson, Kent Bloodsworth, Lori Sussel, Charles Ansong, Julia Laskin
Nanospray Desorption Electrospray Ionization mass spectrometry imaging (nano-DESI MSI) enables ambient imaging of biological samples with high sensitivity and minimal sample pretreatment. Recently, we developed an approach for constant-distance mode MSI using shear force microscopy to precisely control the distance between the sample and the nano-DESI probe. Herein, we demonstrate the power of this approach for robust imaging of pancreatic islets with high spatial resolution of ~11 μm. Pancreatic islets are difficult to characterize using traditional mass spectrometry approaches due to their small size (~100 μm) and molecular heterogeneity...
May 2, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29713963/a-versatile-integrated-ambient-ionization-source-platform
#8
Wanpeng Ai, Honggang Nie, Shiyao Song, Xiaoyun Liu, Yu Bai, Huwei Liu
The pursuit of high-throughput sample analysis from complex matrix demands development of multiple ionization techniques with complementary specialties. A versatile integrated ambient ionization source (iAmIS) platform is proposed in this work, based on the idea of integrating multiple functions, enhancing the efficiency of current ionization techniques, extending the applications, and decreasing the cost of the instrument. The design of the iAmIS platform combines flowing atmospheric pressure afterglow (FAPA) source/direct analysis in real time (DART), dielectric barrier discharge ionization (DBDI)/low-temperature plasma (LTP), desorption electrospray ionization (DESI), and laser desorption (LD) technique...
April 30, 2018: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/29704030/nanospray-desorption-electrospray-ionization-mass-spectrometry-of-untreated-and-treated-probiotic-lactobacillus-reuteri-cells
#9
Agbo-Oma Uwakweh, Joseph N Mwangi, Daniel Todd, Zhenquan Jia, Norman H L Chiu
Mass spectrometry has proven to be a useful technique for rapid identification of bacterial cells. Among various ionization techniques in mass spectrometry, matrix-assisted laser desorption/ionization (MALDI) has been commonly used for the identification of bacterial cells. Recently, MALDI mass spectrometry has also been utilized to distinguish cellular responses. Ambient ionization techniques do support whole bacterial cell analysis, which include desorption electrospray ionization (DESI). Nanospray DESI (nDESI) is a new variant of DESI, and its application to whole-cell mass spectrometry is limited...
April 28, 2018: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/29700557/ambient-desorption-ionization-mass-spectrometry-evolution-from-rapid-qualitative-screening-to-accurate-quantification-tool
#10
REVIEW
Jacob T Shelley, Sunil P Badal, Carsten Engelhard, Heiko Hayen
In this article, some recent trends and developments in ambient desorption/ionization mass spectrometry (ADI-MS) are reviewed, with a special focus on quantitative analyses with direct, open-air sampling. Accurate quantification with ADI-MS is still not routinely performed, but this aspect is considered of utmost importance for the advancement of the field. In fact, several research groups are devoted to the development of novel and optimized ADI-MS approaches. Some key trends include novel sample introduction strategies for improved reproducibility, tailored sample preparation protocols for removing the matrix and matrix effects, and multimode ionization sources...
April 21, 2018: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/29698560/review-and-perspectives-on-the-applications-of-mass-spectrometry-imaging-under-ambient-conditions
#11
Consuelo J Perez, Aafreen K Bagga, Shamina S Prova, Maryam Y Taemeh, Demian R Ifa
Ambient MS-based techniques are performed under ambient conditions in which the ionization and desorption occur in the open environment allowing the direct analysis of molecules on surfaces with minimal or no sample preparation. A selected group of ambient MS techniques demonstrate imaging capabilities that can provide information about the localization of molecules on complex sample surfaces such as biological tissues. 2D, 3D, and multimodal imaging have unlocked an array of applications to systematically address complex problems in many areas of research such as drug monitoring, natural products forensics, and cancer diagnostics...
April 26, 2018: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/29683651/mechanistic-analysis-of-the-c-h-amination-reaction-of-menthol-by-cubr-2-and-selectfluor%C3%A2
#12
Shyam Sathyamoorthi, Yin-Hung Lai, Ryan M Bain, Richard N Zare
The mechanism of the Ritter-type C-H amination reaction of menthol with acetonitrile using CuBr2 , Selectfluor®, and Zn(OTf)2 , first disclosed by Baran and co-workers in 2012, has been studied using a combination of online electrospray ionization mass spectrometry (ESI-MS), continuous UV/vis spectrometric monitoring, and density functional theory calculations. In addition to corroborating Baran's original mechanistic proposal, these studies have uncovered a second pathway to product formation. Density Functional Theory (DFT) calculations show that neither pathway has a barrier that is greater than 6...
April 23, 2018: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29670155/soft-x-ray-heterogeneous-radiolysis-of-pyridine-in-the-presence-of-hydrated-strontium-hydroxyhectorite-and-its-monitoring-by-near-ambient-pressure-photoelectron-spectroscopy
#13
Anthony Boucly, François Rochet, Quentin Arnoux, Jean-Jacques Gallet, Fabrice Bournel, Héloïse Tissot, Virginie Marry, Emmanuelle Dubois, Laurent Michot
The heterogeneous radiolysis of organic molecules in clays is a matter of considerable interest in astrochemistry and environmental sciences. However, little is known about the effects of highly ionizing soft X-rays. By combining monochromatized synchrotron source irradiation with in situ Near Ambient Pressure X-ray Photoelectron Spectroscopy (in the mbar range), and using the synoptic view encompassing both the gas and condensed phases, we found the water and pyridine pressure conditions under which pyridine is decomposed in the presence of synthetic Sr2+ -hydroxyhectorite...
April 18, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29660104/development-of-an-ionization-chamber-for-low-and-medium-energy-photon-dosimetry
#14
Sunil K Singh, M S Kulkarni
Measurement of dose due to low and medium energy X-ray using an ionization chamber needs special considerations as the wall thickness of the detector plays an important role in signal generation. A thin and plane wall ionization chamber having 900 cc volume was developed to study its calibration coefficient with air kerma (Kair) rate and ambient dose equivalent (H*(10)) rate at various X-ray beam qualities generated from a dosimetry grade X-ray machine. Optimized ionization chamber wall thickness was determined through measurements where a flat energy response of the ionization chamber could be established...
April 5, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/29651530/the-requirements-for-low-temperature-plasma-ionization-support-miniaturization-of-the-ion-source
#15
Andreas Kiontke, Frank Holzer, Detlev Belder, Claudia Birkemeyer
Ambient ionization mass spectrometry (AI-MS), the ionization of samples under ambient conditions, enables fast and simple analysis of samples without or with little sample preparation. Due to their simple construction and low resource consumption, plasma-based ionization methods in particular are considered ideal for use in mobile analytical devices. However, systematic investigations that have attempted to identify the optimal configuration of a plasma source to achieve the sensitive detection of target molecules are still rare...
April 13, 2018: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/29619820/online-chemical-characterization-of-food-cooking-organic-aerosols-implications-for-source-apportionment
#16
Ernesto Reyes Villegas, Thomas J Bannan, Michael Le Breton, Archit Mehra, Michael Priestley, Carl Percival, Hugh Coe, James Allan
Food cooking organic aerosols (COA) are one of the main primary sources of submicron particulate matter in urban environments. However, there are still many questions surrounding source apportionment related to instrumentation as well as semi-volatile partitioning as COA evolve rapidly in the ambient air, making source apportionment more complex. Online measurements of emissions from cooking different types of food were performed in a laboratory in order to characterize particles and gases. Aerosol mass spectrometer (AMS) measurements showed that the relative ionization efficiency for OA was higher (1...
April 5, 2018: Environmental Science & Technology
https://www.readbyqxmd.com/read/29607564/ambient-ionization-mass-spectrometry-for-in-situ-analysis-of-intact-proteins
#17
Klaudia I Kocurek, Rian L Griffiths, Helen J Cooper
Ambient surface mass spectrometry is an emerging field which shows great promise for the analysis of biomolecules directly from their biological substrate. In this article, we describe ambient ionization mass spectrometry techniques for the in situ analysis of intact proteins. As a broad approach, the analysis of intact proteins offers unique advantages for the determination of primary sequence variations and post-translational modifications, as well as interrogation of tertiary and quaternary structure and protein-protein/ligand interactions...
April 2, 2018: Journal of Mass Spectrometry: JMS
https://www.readbyqxmd.com/read/29550682/bioanalytical-assay-for-the-quantification-of-the-alk-inhibitor-lorlatinib-in-mouse-plasma-using-liquid-chromatography-tandem-mass-spectrometry
#18
Claudia Spatari, Wenlong Li, Alfred H Schinkel, Gaetano Ragno, Jan H M Schellens, Jos H Beijnen, Rolf W Sparidans
A bio-analytical assay for the first third generation ALK inhibitor lorlatinib in mouse plasma was developed and validated. Ten-μl plasma samples were prepared by adding rucaparib as the internal standard and precipitation of the plasma proteins. For LC-MS/MS analysis, compounds were eluted at 0.5 mL/min and separated on a 3-μm particle-size, polar embedded octadecyl silica column by gradient elution using 0.1% of formic acid (in water) and methanol. Compounds were monitored with positive electrospray ionization using a triple quadrupole mass spectrometer in selected reaction monitoring mode...
April 15, 2018: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
https://www.readbyqxmd.com/read/29537642/characterization-of-a-multi-layer-ionization-chamber-prototype-for-fast-verification-of-relative-depth-ionization-curves-and-spread-out-bragg-peaks-in-light-ion-beam-therapy
#19
Alfredo Mirandola, Giuseppe Magro, Marco Lavagno, Andrea Mairani, Silvia Molinelli, Stefania Russo, Edoardo Mastella, Alessandro Vai, Davide Maestri, Vanessa La Rosa, Mario Ciocca
PURPOSE: To dosimetrically characterize a multi-layer ionization chamber (MLIC) prototype for quality assurance (QA) of pristine integral ionization curves (ICs) and spread-out-Bragg-peaks (SOBPs) for scanning light ion beams. METHODS: QUBE (De.Tec.Tor., Torino, Italy) is a modular detector designed for QA in particle therapy (PT). Its main module is a MLIC detector, able to evaluate particle beam relative depth ionization distributions at different beam energies and modulations...
March 14, 2018: Medical Physics
https://www.readbyqxmd.com/read/29528212/local-electronic-structure-changes-in-polycrystalline-cdte-with-cdcl-2-treatment-and-air-exposure
#20
Morgann Berg, Jason M Kephart, Amit Munshi, Walajabad S Sampath, Taisuke Ohta, Calvin Chan
Postdeposition CdCl2 treatment of polycrystalline CdTe is known to increase the photovoltaic device efficiency. However, the precise chemical, structural, and electronic changes that underpin this improvement are still debated. In this study, spectroscopic photoemission electron microscopy was used to spatially map the vacuum level and ionization energy of CdTe films, enabling the identification of electronic structure variations between grains and grain boundaries (GBs). In vacuo preparation and inert transfer of oxide-free CdTe surfaces isolated the separate effects of CdCl2 treatment and ambient oxygen exposure...
March 21, 2018: ACS Applied Materials & Interfaces
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