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Ambient ionization

Shuai Zhang, Kevin P Driver, François Soubiran, Burkhard Militzer
As one of the simple alkali metals, sodium has been of fundamental interest for shock physics experiments, but knowledge of its equation of state (EOS) in hot, dense regimes is not well known. By combining path integral Monte Carlo (PIMC) results for partially ionized states [B. Militzer and K. P. Driver, Phys. Rev. Lett. 115, 176403 (2015)] at high temperatures and density functional theory molecular dynamics (DFT-MD) results at lower temperatures, we have constructed a coherent equation of state for sodium over a wide density-temperature range of 1...
February 21, 2017: Journal of Chemical Physics
Andreas Bierstedt, Hendrik Kersten, Reto Glaus, Igor B Gornushkin, Ulrich Panne, Jens Riedel
An airborne laser plasma is suggested as an ambient ion source for mass spectrometry. Its fundamental physical properties, such as an excellent spatial and temporal definition, high electron and ion densities and a high effective cross section in maintaining the plasma, make it a promising candidate for future applications. For deeper insights into the plasma properties, the optical plasma emission is examined and compared to mass spectra. The results show a seemingly contradictory behavior, since the emitted light reports the plasma to almost entirely consist of hot elemental ions, while the corresponding mass spectra exhibit the formation of intact molecular species...
February 21, 2017: Analytical Chemistry
Sweccha Joshi, Han Zuilhof, Teris A van Beek, Michel W F Nielen
A simplified coupling of surface plasmon resonance (SPR) immuno-biosensing with ambient ionization mass spectrometry (MS) was developed. It combines two orthogonal analysis techniques: the biosensing capability of SPR and the chemical identification power of high resolution MS. As a proof-of-principle, deoxynivalenol (DON), an important mycotoxin, was captured using an SPR gold chip containing an antifouling layer and monoclonal antibodies against the toxin and, after washing, the chip could be taken out and analyzed by direct spray MS of the biosensor chip to confirm the identity of DON...
February 7, 2017: Analytical Chemistry
Wenjie Liu, Austen Lambert Davis, William F Siems, Du-Lin Yin, Brian H Clowers, Herbert H Hill
Although higher resolving powers are often achieved using ambient pressure drift tube ion mobility mass spectrometry (DT-IMMS) systems, lower duty cycles are often required which directly impacts sensitivity. Moreover, the mechanism of ion gating using Bradbury-Nielsen or Tyndall-Gate configurations routinely results in ion gate depletion effects which discriminate against low mobility ions. This paper reports a new method of ambient pressure ion mobility operation in which inverse ion mobility spectrometry is coupled to a time of flight mass spectrometer to improve sensitivity and minimize the effects of ion gate depletion...
February 6, 2017: Analytical Chemistry
Xin Yan, Xin Li, Chengsen Zhang, Yang Xu, R Graham Cooks
A change in enzyme activity has been used as a clinical biomarker for diagnosis and is useful in evaluating patient prognosis. Current laboratory measurements of enzyme activity involve multi-step derivatization of the reaction products followed by quantitative analysis of these derivatives. This study simplified the reaction systems by using only the target enzymatic reaction and directly detecting its product. A protocol using paper spray mass spectrometry for identifying and quantifying the reaction product has been developed...
January 31, 2017: Journal of the American Society for Mass Spectrometry
Avinash Dalmia
A rapid method, with minimalsample preparation and nochromatography, was developedfor analyzing food samples suchasolive oil and pomegranatejuice to measure adulterationwith cheaper ingredientsusing the novel Direct SampleAnalysis<sup>™</sup> (DSA) ion source inconjunction with a time-of-flight(TOF)-MS. In less than 30 s, withminimal sample preparationand method development,adulteration of olive oil andpomegranate juice with cheaperseed oils and fruit juices,respectively, was measured withDSA/TOF-MS...
December 15, 2016: Journal of AOAC International
Joseph M Mannion, Matthew S Wellons, Charles R Shick, Glenn A Fugate, Brian A Powell, Scott M Husson
Degassing is a common preparation technique for rhenium filaments used for thermal ionization mass spectrometric analysis of actinides, including plutonium. Although optimization studies regarding degassing conditions have been reported, little work has been done to characterize filament aging after degassing. In this study, the effects of filament aging after degassing were explored to determine a "shelf-life" for degassed rhenium filaments, and methods to limit filament aging were investigated. Zone-refined rhenium filaments were degassed by resistance heating under high vacuum before exposure to ambient atmosphere for up to 2 months...
January 2017: Heliyon
Z Takats, N Strittmatter, J S McKenzie
Ambient ionization mass spectrometry was developed as a sample preparation-free alternative to traditional MS-based workflows. Desorption electrospray ionization (DESI)-MS methods were demonstrated to allow the direct analysis of a broad range of samples including unaltered biological tissue specimens. In contrast to this advantageous feature, nowadays DESI-MS is almost exclusively used for sample preparation intensive mass spectrometric imaging (MSI) in the area of cancer research. As an alternative to MALDI, DESI-MSI offers matrix deposition-free experiment with improved signal in the lower (<500m/z) range...
2017: Advances in Cancer Research
Hazem H Abdelmaksoud, Taryn M Guinan, Nicolas H Voelcker
Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) is a high-throughput analytical technique ideally suited for small-molecule detection from different bodily fluids (e.g., saliva, urine, and blood plasma). Many SALDI-MS substrates require complex fabrication processes and further surface modifications. Furthermore, some substrates show instability upon exposure to ambient conditions and need to be kept under special inert conditions. We have successfully optimized mesoporous germanium (meso-pGe) using bipolar electrochemical etching and efficiently applied meso-pGe as a SALDI-MS substrate for the detection of illicit drugs such as in the context of workplace, roadside, and antiaddictive drug compliance...
February 6, 2017: ACS Applied Materials & Interfaces
Dian E Romonosky, Ying Li, Manabu Shiraiwa, Alexander Laskin, Julia Laskin, Sergey A Nizkorodov
Formation of secondary organic aerosols (SOA) from biogenic volatile organic compounds (BVOC) occurs via O3- and OH-initiated reactions during the day and reactions with NO3 during the night. We explored the effect of these three oxidation conditions on the molecular composition and aqueous photochemistry of model SOA prepared from two common BVOC. A common monoterpene, α-pinene, and sesquiterpene, α-humulene, were used to form SOA in a smog chamber via BVOC + O3, BVOC + NO3, and BVOC + OH + NOx oxidation...
February 6, 2017: Journal of Physical Chemistry. A
Quan Yu, Jianchao Zhang, Kai Ni, Xiang Qian, Xiaohao Wang
A single gas-assisted electrospray ion source developed for ambient mass spectrometry is introduced in this paper. Simultaneous self-aspiration and electrospray could be achieved by using a constant sheath gas flow supplied from a mini air pump. A gas dynamic study of the spray module is carried out for structural optimization. The entire device exhibits a simplified design and has been systematically characterized through both simulated and experimental investigations. According to the results, the ion source exhibited satisfactory stability and the ability for quantitative operation in routine electrospray ionization mass spectrometry...
January 11, 2017: Journal of Mass Spectrometry: JMS
Yang Liu, Ning Liu, Ya-Nan Zhou, Lan Lin, Lan He
With a great quantity of solid dosage tested by dissolution technology, developing a rapid and sensitive method to access the content of drug within dissolution media is highly desired by analysts and scientists. Traditionally, dissolution media is not compatible with mass spectrometry since the inorganic salts in the media might damage the mass spectrometer. Here, paper spray ionization mass spectrometry (PSI-MS), one of the ambient mass spectrometry technologies, is developed to characterize the content of drugs in dissolution media...
March 20, 2017: Journal of Pharmaceutical and Biomedical Analysis
Mathilde Farenc, Matthias Witt, Kirsten Craven, Caroline Barrère-Mangote, Carlos Afonso, Pierre Giusti
Polyolefins such as polyethylene (PE) and polypropylene (PP) are often characterized from their pyrolysis products by Py-MS. Nowadays the development of plasma-based direct probe atmospheric pressure sources allow the direct analysis of these polymers. These sources operate at atmospheric pressure, which implies a limited control of the ionization conditions. It was shown that side reactions could occur with species present in air, such as O2, which may lead to the formation of oxidized compounds. In this work, ion mobility-mass spectrometry (IM-MS) and Fourier transform ion cyclotron resonance mass spectrometry (FTICR) were used for the exhaustive characterization of the PP and PE pyrolysis ions produced using plasma-based atmospheric pressure ion sources...
January 3, 2017: Journal of the American Society for Mass Spectrometry
Shama F Barna, Kyle E Jacobs, Glennys A Mensing, Placid M Ferreira
This paper reports a liquid-free, mask-less electrochemical direct-write lithographic technique using an atomic force microscopy (AFM) probe for writing silver nanostructures in minutes on an optically transparent substrate. Under ambient conditions, silver is locally and controllably extracted to the surface of superionic (AgI)0.25 (AgPO3)0.75 glass by bringing a conductive AFM probe tip in contact with it, biasing the probe with a negative voltage, and regulating the resulting current. The growth mechanism of the resulting nanostructure is explored by extracting silver with a stationary AFM tip on the surface of the silver...
January 3, 2017: Nanotechnology
Xiaoxiao Ma, Zheng Ouyang
Ambien ionization and miniaturization of mass spectrometers are two fields in mass spectrometry that have advanced significantly in the last decade. The integration of the techniques developed in these two fields is leading to the development of complete miniature analytical systems that can be used for on-site or point-of-care analysis by non-expert users. In this review, we report the current status of development in ambient ionization and miniature mass spectrometers, with an emphasis on those techniques with potential impact on the point-of-care (POC) diagnostics...
December 2016: Trends in Analytical Chemistry: TRAC
Tianyi Li, Liusheng Fan, Yingfeng Wang, Xuebin Huang, Jianguo Xu, Jinxing Lu, Mei Zhang, Wei Xu
Typically dealing with practical samples with very complex matrices, ambient ionization mass spectrometry suffers from low detection sensitivity. In this study, molecular imprinting technology was explored and integrated with the membrane electrospray ionization (MESI) method for direct sample analyses. By enriching targeted analytes on molecularly imprinted membranes (MIMs), improvement (by 10- to 50-fold) in the limit of quantitation could be achieved, compared to conventional nanoelectrospray ionization methods or other ambient ionization methods...
February 7, 2017: Analytical Chemistry
Offer M Zeiri, Andrew P Storey, Steven J Ray, Gary M Hieftje
A new direct-current microplasma-based flowing atmospheric pressure afterglow (FAPA) source was developed for use in ambient desorption-ionization mass spectrometry. The annular-shaped microplasma is formed in helium between two concentric stainless-steel capillaries that are separated by an alumina tube. Current-voltage characterization of the source shows that this version of the FAPA operates in the normal glow-discharge regime. A glass surface placed in the path of the helium afterglow reaches temperatures of up to approximately 400 °C; the temperature varies with distance from the source and helium flow rate through the source...
February 1, 2017: Analytica Chimica Acta
Kailin Liu, Shiji Xu, Minghuan Zhang, Yahong Kou, Xiaomao Zhou, Kun Luo, Lifeng Hu, Xiangying Liu, Min Liu, Lianyang Bai
The toxicity of ionizable organic compounds to organisms depends on the pH, which therefore affects risk assessments of these compounds. However, there is not a direct chemical method to predict the toxicity of ionizable organic compounds. To determine whether hollow-fiber liquid-phase microextraction (HF-LPME) is applicable for this purpose, a three-phase HF-LPME was used to measure sulfadiazine and estimate its toxicity to Daphnia magna in solutions of different pH. The result indicated that the sulfadiazine concentrations measured by HF-LPME decreased with increasing pH, which is consistent with the decreased toxicity...
December 22, 2016: Scientific Reports
Zachary E Lawton, Angelica Traub, William L Fatigante, Jose Mancias, Adam E O'Leary, Seth E Hall, Jamie R Wieland, Herbert Oberacher, Michael C Gizzi, Christopher C Mulligan
Forensic evidentiary backlogs are indicative of the growing need for cost-effective, high-throughput instrumental methods. One such emerging technology that shows high promise in meeting this demand while also allowing on-site forensic investigation is portable mass spectrometric (MS) instrumentation, particularly that which enables the coupling to ambient ionization techniques. While the benefits of rapid, on-site screening of contraband can be anticipated, the inherent legal implications of field-collected data necessitates that the analytical performance of technology employed be commensurate with accepted techniques...
December 20, 2016: Journal of the American Society for Mass Spectrometry
Sebastian Brandt, Felix David Klute, Alexander Schütz, Joachim Franzke
Dielectric barrier discharges are used for analytical applications as dissociative source for optical emission spectrometry and for ambient-ionization techniques. In the range of ambient-ionization techniques it has attracted much attention in fields like food safety, biological analysis, mass spectrometry for reaction monitoring and imaging forensic identification. In this review some examples are given for the application as desorption/ionization source as well as for the sole application as ionization source with different sample introductions...
January 25, 2017: Analytica Chimica Acta
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