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Journal articles on the topic 'Ionization method'

Author: Grafiati

Published: 28 May 2022

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1

Hirabayashi, Atsumu, Minoru Sakairi, and Hideaki Koizumi. "Sonic Spray Ionization Method for Atmospheric Pressure Ionization Mass Spectrometry." Analytical Chemistry 66, no. 24 (1994): 4557–59. http://dx.doi.org/10.1021/ac00096a025.

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2

Wu, Fangling, and Chuan-Fan Ding. "Electro-Filtering Paper Spray Ionization Method." Journal of Infectiology 2, no. 3 (2019): 4–7. http://dx.doi.org/10.29245/2689-9981/2019/3.1140.

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3

Sulimenkov, Ilya V., Kamil R. Taziev, Vladimir S. Brusov, and Viatcheslav I. Kozlovskiy. "Using matrix-assisted ionization method for mass spectral identification of fullerene-dye conjugates." European Journal of Mass Spectrometry 26, no. 6 (2020): 419–24. http://dx.doi.org/10.1177/1469066720970520.

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Traditional soft ionization methods are not always suitable for mass spectral analysis of complex compounds. Factors such as laser radiation and heating resulting in fragmentations of sample molecules in the case of matrix-assisted laser desorption/ionization and difficulties in preparing suitable sample solutions in the case of electrospray ionization make it impossible to use these methods in some cases. Matrix-assisted ionization was used to analyze products of chemical synthesis involving pyropheophorbide and fullerene. Mass spectra were acquired using a simple effective modification of the Exactive Orbitrap mass spectrometer electrospray interface. Reliable identification of pyropheophorbide-fullerene dyad ions and its derivatives was carried out. An experimental comparison of a matrix-assisted ionization and an electrospray ionization technique demonstrated the significant advantage in sensitivity to the ions under study (approximately 20 times higher) of the matrix-assisted ionization method in this particular study.

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4

Bartnik, Andrzej, Wojciech Skrzeczanowski, Henryk Fiedorowicz, et al. "Photoionized plasmas induced in molecular gases by extreme ultraviolet and X-ray pulses." EPJ Web of Conferences 167 (2018): 03003. http://dx.doi.org/10.1051/epjconf/201816703003.

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In this work a laser-produced plasma (LPP) source was used to create low temperature plasmas. An extreme ultraviolet and soft X-ray (EUV/SXR) radiation pulse was used for ionization of molecular gases, injected into a vacuum chamber synchronously with the EUV/SXR pulse. Energies of photons exceeding 100 eV were sufficient for dissociative ionization, ionization of atoms or even ions. The resulting photoelectrons had also enough energy for further ionizations or excitations. Time resolved UV/VIS spectra, corresponding to single charged ions, molecules and molecular ions, were recorded. For spectral lines, corresponding to radiative transitions in F II and S II ions, electron temperature was calculated based on a Boltzmann plot method. Numerical simulations of the molecular spectra were fitted to the experimental spectra allowing for determination of vibrational and rotational temperatures.

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5

Guo, Li, Mingqing Liu, Ronghua Lu, Shensheng Han, and Jing Chen. "Analysis of above-threshold ionization by “Wigner-distribution-like function” method." Laser and Particle Beams 37, no. 4 (2019): 448–62. http://dx.doi.org/10.1017/s0263034619000569.

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AbstractAbove-threshold ionization (ATI) is one of the most fundamental processess when atoms or molecules are subjected to intense laser fields. Analysis of ATI process in intense laser fields by a Wigner-distribution-like (WDL) function is reviewed in this paper. The WDL function is used to obtain various time-related distributions, such as time-energy distribution, ionization time distribution, and time-emission angle distribution and so on, of atoms in laser field pulses with different laser parameters. For the linearly polarized laser pulses, the time-energy distribution intuitively shows from a quantum point of view the relationship between the ionization moment and the final energy and clearly reveals the origin of interference structures in the photoelectron spectrum. In particular, for linearly polarized few-cycle laser pulses, all calculated distributions show the dependence of electron behavior on the ionization time, emission direction, and carrier-envelope phase (CEP). For elliptically polarized few-cycle pulses, we calculate the angular distribution, ionization time distribution, and time-emission distribution, which are compared with the semiclassical calculations. Analysis shows that the offset angle (difference between positions of the peaks in the angular distributions obtained by two methods) in the angular distributions does not correspond to the offset time (difference between positions of the peaks in the ionization time distributions obtained by two methods) in the ionization time distributions, which implies that the attosecond angular streaking technique based on this correspondence between the offset angle and time is in principle inaccurate. Furthermore, the offset time cannot be interpreted as tunneling time.

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6

Dąbek, Józef, and Stanislaw Halas. "Physical Foundations of Rhenium-Osmium Method - A Review." Geochronometria 27, no. -1 (2007): 23–26. http://dx.doi.org/10.2478/v10003-007-0011-4.

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Physical Foundations of Rhenium-Osmium Method - A Review A newly acquired mass spectrometer MI 1201 by the Mass Spectrometry Laboratory will be adapted to determine rhenium and osmium isotope concentrations using negative thermal ionization mass spectrometry (NTIMS). We describe the principle of the Re-Os dating technique and the thermal ionization phenomena which lead to high precision isotope analysis on NTIMS.

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7

de Avillez, Miguel A., Mauro Guerra, José Paulo Santos, and Dieter Breitschwerdt. "Relativistic electron impact ionization cross sections of carbon ions and application to an optically thin plasma." Astronomy & Astrophysics 631 (October 17, 2019): A42. http://dx.doi.org/10.1051/0004-6361/201935337.

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Context. Ionization through electron impact is a fundamental process associated with the evolution of the ionic structure and emissivity of astrophysical plasmas. Over several decades substantial efforts have been made to measure and calculate the ionization cross sections of ionization through electron impact of different ions shell by shell, in particular, of carbon ions. Spectral emission codes use electron-impact ionization cross sections and/or rates taken from different experimental and theoretical sources. The theoretical cross sections are determined numerically and include a diversity of quantum mechanical methods. The electron-impact ionization database therefore is not uniform in the methods, which makes it hard to determine the reason for the deviations with regard to experimental data. In many cases only total ionization rates for Maxwell–Boltzmann plasmas are available, which makes calculating inner-shell ionization in collisional-radiative models using thermal and nonthermal electron distribution functions difficult. A solution of this problem is the capability of generating the cross sections with an analytical method using the minimum number of atomic parameters. In this way, uniformity in the database is guaranteed, and thus deviations from experiments are easily identified and traced to the root of the method. Aims. The modified relativistic binary encounter Bethe (MRBEB) method is such a simple analytical scheme based on one atomic parameter that allows determining electron-impact ionization cross sections. This work aims the determination of K- and L-shell cross sections of the carbon atom and ions using the MRBEB method and show their quality by: (i) comparing them with those obtained with the general ionization processes in the presence of electrons and radiation (GIPPER) code and the flexible atomic code (FAC), and (ii) determining their effects on the ionic structure and cooling of an optically thin plasma. Methods. The MRBEB method was used to calculate the inner-shells cross sections, while the plasma calculations were carried out with the collisional+photo ionization plasma emission software (CPIPES). The mathematical methods used in this work comprise a modified version of the double-exponential over a semi-finite interval method for numerical integrations, Gauss-elimination method with scaled partial pivoting for the solution of systems of linear equations, and an iterative least-squares method to determine the fits of ionization cross sections. Results. The three sets of cross sections show deviations among each other in different energy regions. The largest deviations occur near and in the peak maximum. Ion fractions and plasma emissivities of an optically thin plasma that evolves under collisional ionization equilibrium, derived using each set of cross sections, show deviations that decrease with increase in temperature and ionization degree. In spite of these differences, the calculations using the three sets of cross sections agree overall. Conclusions. A simple model like the MRBEB is capable of providing cross sections similar to those calculated with more sophisticated quantum mechanical methods in the GIPPER and FAC codes.

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8

Cho, Kyung-Cho, Byoung-Kyu Cho, Jin Woo Jung, Ye Ji Lee, Eun Bong Lee, and Eugene C. Yi. "SRM-MS Method Development for Hepcidin-25 Peptide." Journal of Analytical Methods in Chemistry 2018 (June 14, 2018): 1–7. http://dx.doi.org/10.1155/2018/9653747.

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As advanced mass spectrometry- (MS-) based hepcidin analysis offers to overcome the limitations in analytical methods using antihepcidin, further improvement of MS detection sensitivity for the peptide may enhance the diagnostic value of the hepcidin for various iron-related disorders. Here, improved MS detection sensitivity of hepcidin has been achieved by reducing the disulfide bonds in hepcidin, by which proton accessibility increased, compared to the intact hepcidin peptide. Comparing the ionization efficiencies of reduced and nonreduced forms of hepcidin, the reduced form of hepcidin showed an increase in ionization efficiency more than two times compared to the nonreduced form of hepcidin. We also demonstrated improved detection sensitivity of the peptide in SRM assay. We observed a significant improvement of detection sensitivity at the triple-quadrupole MS platform, that the ionization efficiency increased at least twice more, and that the limit of detection (LOD) increased more than 10 times in the concentration ranges of 1 fmol to 10 fmol of hepcidin. In this study, we demonstrated the usefulness of the hepcidin modification for overall enhancement of the ionization efficiencies of the hepcidin peptide in the MS-based quantitative measurement assay.

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9

Grotemeyer, J., J. Lindner, C. Köster, and E. W. Schlag. "Multiphoton ionization mass spectrometry: Method and applications." Journal of Molecular Structure 217 (March 1990): 51–68. http://dx.doi.org/10.1016/0022-2860(90)80351-j.

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10

Wong, Philip S. H., Shuguang Ma, and R. G. Cooks. "Ionization Energy Determination by the Kinetic Method." Analytical Chemistry 68, no. 23 (1996): 4254–56. http://dx.doi.org/10.1021/ac960566z.

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11

Verenchikov, A. N., and A. P. Kolosov. "A soft ionization method for semivolatile compounds." Journal of Analytical Chemistry 70, no. 13 (2015): 1527–32. http://dx.doi.org/10.1134/s1061934815130092.

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12

Constapel, M., M. Schellenträger, O. J. Schmitz, et al. "Atmospheric-pressure laser ionization: a novel ionization method for liquid chromatography/mass spectrometry." Rapid Communications in Mass Spectrometry 19, no. 3 (2005): 326–36. http://dx.doi.org/10.1002/rcm.1789.

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13

Gall, L. N., and A. G. Kouzmin. "Creeping Discharge Mass Spectrometry: A New Method for Elemental Analysis of Dielectrics." European Journal of Mass Spectrometry 8, no. 3 (2002): 207–12. http://dx.doi.org/10.1255/ejms.493.

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The creeping discharge (CD), a special kind of surface discharge, is proposed as a method of ionization in mass spectrometry for elemental analysis of dielectrics. Characteristic features of creeping discharge ionization mass spectra of dielectric samples were studied. An yttrium oxide standard sample and dielectrics of high electric strength were successfully analyzed. The results of analysis of the ion charge state in creeping discharge are presented. A theoretical model of creeping discharge ionization is offered.

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14

Pindzola, Michael S., Stuart D. Loch, and James P. Colgan. "Electron-Impact Ionization of Heavy Atoms Using the Time-Dependent Close-Coupling Method." Atoms 9, no. 2 (2021): 32. http://dx.doi.org/10.3390/atoms9020032.

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The time-dependent close-coupling method has been recently applied to calculate electron-impact direct ionization cross sections for the Kr, W, and Pb atoms. An overview is presented for these three heavy neutral atom systems. When the direct ionization cross sections are combined with excitation-autoionization cross sections, the total ionization cross sections were found to be in reasonable agreement with crossed-beams measurements for Kr and Pb.

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15

de Avillez, Miguel A., Gervásio J. Anela, and Dieter Breitschwerdt. "Variability of the adiabatic parameter in monoatomic thermal and non-thermal plasmas." Astronomy & Astrophysics 616 (August 2018): A58. http://dx.doi.org/10.1051/0004-6361/201832948.

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Context. Numerical models of the evolution of interstellar and integalactic plasmas often assume that the adiabatic parameter γ (the ratio of the specific heats) is constant (5/3 in monoatomic plasmas). However, γ is determined by the total internal energy of the plasma, which depends on the ionic and excitation state of the plasma. Hence, the adiabatic parameter may not be constant across the range of temperatures available in the interstellar medium. Aims. We aim to carry out detailed simulations of the thermal evolution of plasmas with Maxwell–Boltzmann and non-thermal (κ and n) electron distributions in order to determine the temperature variability of the total internal energy and of the adiabatic parameter. Methods. The plasma, composed of H, He, C, N, O, Ne, Mg, Si, S, and Fe atoms and ions, evolves under collisional ionization equilibrium conditions, from an initial temperature of 109 K. The calculations include electron impact ionization, radiative and dielectronic recombinations and line excitation. The ionization structure was calculated solving a system of 112 linear equations using the Gauss elimination method with scaled partial pivoting. Numerical integrations used in the calculation of ionization and excitation rates are carried out using the double-exponential over a semi-finite interval method. In both methods a precision of 10−15 is adopted. Results. The total internal energy of the plasma is mainly dominated by the ionization energy for temperatures lower than 8 × 104 K with the excitation energy having a contribution of less than one percent. In thermal and non-thermal plasmas composed of H, He, and metals, the adiabatic parameter evolution is determined by the H and He ionizations leading to a profile in general having three transitions. However, for κ distributed plasmas these three transitions are not observed for κ < 15 and for κ < 5 there are no transitions. In general, γ varies from 1.01 to 5/3. Lookup tables of the γ parameter are presented as supplementary material.

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16

Sholokhova, Anastasiya Yu, Svetlana A. Borovikova, Sergey A. Prikhod'ko, and Alexey K. Buryak. "Ionization of ionic liquids under laser desorption/ionization." Сорбционные и хроматографические процессы 20, no. 5 (2020): 565–71. http://dx.doi.org/10.17308/sorpchrom.2020.20/3048.

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Despite various studies of ILs as MALDI matrices, however, so far no relationship has been foundbetween the composition of ILs and their ability to serve as «good» matrices. For a preliminary experiment,in order to evaluate the characteristics of ILs before being used as a matrix in MALDI-MS, it is necessary tostudy the mass spectral behavior for the matrices themselves under LDI conditions. Therefore, the purpose of this work was to analyse ion liquids based on the cation imidazolium in combination with different types ofanions by the LDI method. Ionic liquids were synthesized in the Laboratory of catalytic processes for thesynthesis of organoelement compounds of G.K. Boreskov Institute of catalysis SB RAS (Novosibirsk). Itshould be noted that this ionic liquid was first synthesized in this Laboratory. Analyses were performed usinga Bruker UltraFlex II time of-flight mass spectrometer. Eleven ion liquids based on substituted cation imidazolium in combination with different types of anions were analysed by method laser desorption/ionization in the paper. In all mass spectra of ionic liquids obtained in the positive ion mode, cation produced a major peak and its fragmented ions. Homologous series characterized by the loss of the methyl group have been recorded. According to the more stable carbon-carbon or nitrogen bond in the heterocyclic system than in the carbon-carbon bond in the aliphatic, ion peaks are observed in the mass spectra, characteristic of the loss of methyl fragments from the aliphatic chain. In the LDI spectra obtained in the negative ion mode, the signals of the anions of ionic liquids and their fragments were observed. The combined use of the spectra obtained in positive and negative mode makes it possible to increase the reliability of identification. This makes it possible to use the revealed patterns of fragmentation for the structural analysis of ionic liquids. The analyzed ILs can be used as MALDI matrices, because they do not form dimers, assassinates, are characterized by the absence of adducts with metal ions, which is important for their further use as matrices. BMIMC6F5BF3 was first described by the LDI-MS method. It was shown that the observed fragmentation of the molecular ion of this IL is typical for most ILs with similar cations.

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17

Pagnotti, Vincent S., Nicholas D. Chubatyi, and Charles N. McEwen. "Solvent Assisted Inlet Ionization: An Ultrasensitive New Liquid Introduction Ionization Method for Mass Spectrometry." Analytical Chemistry 83, no. 11 (2011): 3981–85. http://dx.doi.org/10.1021/ac200556z.

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18

Sekine, S., A. Iwasaki, A. Kurokawa, S. Ichimura, K. Kokubun, and H. Shimizu. "Simultaneous measurement of total and partial pressure and ionization volume by laser ionization method." Vacuum 47, no. 6-8 (1996): 553–55. http://dx.doi.org/10.1016/0042-207x(96)00018-8.

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19

Pardo-Montero, Juan, Jose Paz-Martín, Luis Brualla-Gónzalez, and Faustino Gómez. "Online Recombination Correction in Dosimetry with Arrays of Ionization Chambers: Application to FFF and UHDR Radiotherapy." Applied Sciences 11, no. 21 (2021): 10083. http://dx.doi.org/10.3390/app112110083.

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Recombination of charge carriers can affect the response of ionization detectors used for the dosimetry of radiotherapy fields. In this work, we present a method for correcting online the recombination effects in arrays of ionization chambers irradiated with time-varying dose rates. The method is based on the characterization of the dose rate/recombination response of the detector, and the measurement of the instant ionization current in the detector, rather than the integrated charge. The proposed method was investigated with simulations of the response of different air and liquid ionization chambers in situations where recombination can be large. In addition, we experimentally investigated the application of the method with an in-house-developed liquid-filled ionization chamber. The proposed online correction method can compensate for recombination losses and seems feasible to implement in the software of ionization arrays/detectors used for the dosimetry of radiotherapy fields.

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20

KATO, Hiroshi, Morio ISHIHARA, and Munetaka NAKATA. "New Deconvolution Method for Electrospray Ionization Mass Spectrometry." Journal of the Mass Spectrometry Society of Japan 48, no. 6 (2000): 373–79. http://dx.doi.org/10.5702/massspec.48.373.

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21

Bouchouxa, Guy, Danielle Leblanc, and Michel Sablier. "Determination of ionization energies by the thermokinetic method." International Journal of Mass Spectrometry 210-211 (September 2001): 189–201. http://dx.doi.org/10.1016/s1387-3806(01)00449-3.

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22

Belyakov Vasilievich, Vladimir, Maksim Matusko Aleksandrovich, Anatoly Golovin Vladimirovich, and Evgeniy Gromov Anatolovich. "Advanced sample ionization method in ion mobility spectrometer." Facta universitatis - series: Electronics and Energetics 29, no. 4 (2016): 613–20. http://dx.doi.org/10.2298/fuee1604613b.

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23

Poutsma, John C., Randal A. Seburg, Leonard J. Chyall, et al. "Combining Electrospray Ionization and the Flowing Afterglow Method." Rapid Communications in Mass Spectrometry 11, no. 5 (1997): 489–93. http://dx.doi.org/10.1002/(sici)1097-0231(199703)11:5<489::aid-rcm896>3.0.co;2-l.

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24

Fang, Xiaohua, Dirk Lummerzheim, and Charles H. Jackman. "Proton impact ionization and a fast calculation method." Journal of Geophysical Research: Space Physics 118, no. 8 (2013): 5369–78. http://dx.doi.org/10.1002/jgra.50484.

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25

Sampson, Douglas H., and Hong Lin Zhang. "Rapid-ionization approach based on the factorization method." Physical Review A 45, no. 3 (1992): 1657–69. http://dx.doi.org/10.1103/physreva.45.1657.

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26

Kokubun, K., S. Ichimura, H. Shimizu, and S. Sekine. "Pressure measurement method using laser ionization for xhv." Vacuum 44, no. 5-7 (1993): 657–59. http://dx.doi.org/10.1016/0042-207x(93)90118-t.

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27

Aida, Mari, Takahiro Iwai, Yuki Okamoto, Hidekazu Miyahara, Yasuo Seto, and Akitoshi Okino. "Development of an ionization method using hydrogenated plasma for mass analysis of surface adhesive compounds." Journal of Analytical Atomic Spectrometry 33, no. 4 (2018): 578–84. http://dx.doi.org/10.1039/c7ja00314e.

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This paper proposes an ionization method that adds a small amount of hydrogen to the helium plasma to generate protons in the sample ionization source. Using this, mass spectrometry was performed on adhesive compounds.

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28

Wang, Lewei, Tsubasa Omoda, Kiichirou Koyasu, and Tatsuya Tsukuda. "Controlled Synthesis of Diphosphine-Protected Gold Cluster Cations Using Magnetron Sputtering Method." Molecules 27, no. 4 (2022): 1330. http://dx.doi.org/10.3390/molecules27041330.

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We demonstrated, for the first time, atomically precise synthesis of gold cluster cations by magnetron sputtering of a gold target onto a polyethylene glycol (PEG) solution of 1,3-bis(diphenylphosphino)propane (Ph2PCH2CH2CH2PPh2, dppp). UV-vis absorption spectroscopy and electrospray ionization mass spectrometry revealed the formation of cationic species, such as [Au(dppp)n]+ (n = 1, 2), [Au2(dppp)n]2+ (n = 3, 4), [Au6(dppp)n]2+ (n = 3, 4), and [Au11(dppp)5]3+. The formation of [Au(dppp)2]+ was ascribed to ionization of Au(dppp)2 by the reaction with PEG, based on its low ionization energy, theoretically predicted, mass spectrometric detection of deprotonated anions of PEG. We proposed that [Au(dppp)2]+ cations thus formed are involved as key components in the formation of the cluster cations.

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29

Kim, Donghwi, Un Hyuk Yim, Byungjoo Kim, Sangwon Cha, and Sunghwan Kim. "Paper Spray Chemical Ionization: Highly Sensitive Ambient Ionization Method for Low- and Nonpolar Aromatic Compounds." Analytical Chemistry 89, no. 17 (2017): 9056–61. http://dx.doi.org/10.1021/acs.analchem.7b01733.

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30

Grotemeyer, Jürgen, Ulrich Boesl, Klaus Walter, and Edward W. Schlag. "A general soft ionization method for mass spectrometry: Resonance-enhanced multi-photon ionization of biomolecules." Organic Mass Spectrometry 21, no. 10 (1986): 645–53. http://dx.doi.org/10.1002/oms.1210211008.

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31

Trimpin, Sarah, and Ellen D. Inutan. "Matrix Assisted Ionization in Vacuum, a Sensitive and Widely Applicable Ionization Method for Mass Spectrometry." Journal of The American Society for Mass Spectrometry 24, no. 5 (2013): 722–32. http://dx.doi.org/10.1007/s13361-012-0571-z.

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32

Derpmann, Valerie, David Mueller, Iustinian Bejan, et al. "Capillary Atmospheric Pressure Electron Capture Ionization (cAPECI): A Highly Efficient Ionization Method for Nitroaromatic Compounds." Journal of The American Society for Mass Spectrometry 25, no. 3 (2014): 329–42. http://dx.doi.org/10.1007/s13361-013-0761-3.

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33

Honda, Aki, Yoshio Suzuki, and Koji Suzuki. "Mass probe-assisted ionization method for total analysis of biomolecules with electrospray ionization–mass spectrometry." Chemical Record 6, no. 2 (2006): 100–106. http://dx.doi.org/10.1002/tcr.20075.

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34

BUET, C., S. CORDIER, and P. A. RAVIART. "MULTIFLUID IONIZATION MODELS." Mathematical Models and Methods in Applied Sciences 12, no. 01 (2002): 17–48. http://dx.doi.org/10.1142/s0218202502001532.

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In this paper, we present a multi-fluid ionization model. We prove that this stationary, mono-dimensional model has a maximal solution which is not global at variance with the mono-species case and we present a numerical method for solving this highly singular system of ordinary differential equations. Numerical results are compared with those obtained for other models.

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35

Zhang, Gui Yin, Yi Dong Jin, and Hai Ming Zheng. "Detection of Atmospheric Pollutant NO With the Method of Resonant-Enhanced Multiphoton Ionization." Applied Mechanics and Materials 209-211 (October 2012): 1596–99. http://dx.doi.org/10.4028/www.scientific.net/amm.209-211.1596.

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NO is one of the key substances of air pollution. This paper presents the use of the technique of resonant enhanced multi-photon ionization (REMPI) for NO ambient detection. NO is ionized by absorbing four photons and via A2Σ intermediate resonant state when use 452.4nm laser as radiation source. A physical model concerning the ionization process is presented. It is shown that the ion signal depends on laser character and the dynamic parameters of NO. Two-photon absorption and ionization cross section about the resonant state are obtained from the ion decay curve and the model. The detection limit of this work, which can reach 1.4 ppm, is determined by measuring the variation of the ion signal with the concentration of NO.

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36

Schulz, Sabine, Sebastian Wagner, Stefanie Gerbig, et al. "DESI MS based screening method for phthalates in consumer goods." Analyst 140, no. 10 (2015): 3484–91. http://dx.doi.org/10.1039/c5an00338e.

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37

Stout, Steven J., Enaksha Wickremesinhe, Adrian R. daCunha, and Alisa Khunachak. "Confirmation of Moxidectin Residues in Cattle Fat by Liquid Chromatography/Mass Spectrometry." Journal of AOAC INTERNATIONAL 83, no. 6 (2000): 1446–50. http://dx.doi.org/10.1093/jaoac/83.6.1446.

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Abstract Moxidectin, a potent new endo- and ectoparasitic agent, is determined in cattle tissues by liquid chromatography (LC) with fluorescence detection. The original confirmatory method for moxidectin in cattle fat, the target tissue for regulatory purposes, was LC with mass spectrometry (MS) using thermospray (TSP) ionization and selected ion monitoring. As newer ionization techniques for LC/MS made TSP obsolete and with the availability of a new generation of benchtop LC/MS instrumentation, the confirmation of moxidectin in cattle fat was re-evaluated. The ionization techniques of atmospheric pressure chemical ionization versus electrospray ionization, the detection techniques of single-stage MS versus tandem MS, and the instrumentation of ion trap versus quadrupole were investigated. The final confirmatory method was based on full-scan single-stage MS. Even with full-scan detection, the analysis required at least 10-fold less extract than the original TSP method. The applicability of this new confirmatory method was demonstrated on both ion trap and quadrupole instruments.

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38

Grechnikov, Alexander A., Alexey S. Borodkov, Yaroslav O. Simanovsky, and Sergey M. Nikiforov. "Silicon surface assisted laser desorption ionization mass spectrometry for quantitative analysis." European Journal of Mass Spectrometry 27, no. 2-4 (2021): 84–93. http://dx.doi.org/10.1177/14690667211006017.

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The approach to quantitative analysis by silicon Surface Assisted Laser Desorption Ionization Mass Spectrometry (Si-SALDI) is proposed. The approach is based on the new method for forming an active surface layer on a silicon substrate by exposing to laser radiation directly in the ion source of a mass spectrometer. The method can be used repeatedly on the same substrate, providing high reproducibility of its surface ionization properties and high ionization efficiency of organic compounds. Within the proposed approach, the methods of improvement of signal reproducibility are also considered, including continuous monitoring of the silicon surface ionization properties using a Knudsen effusion cell; scanning the surface of a silicon substrate with a laser beam; selecting the optimal value of laser fluence and using a reproducible sample introduction technique. It is demonstrated that this approach can be successfully applied to quantify clinically relevant concentrations of pharmaceutical drugs in extracts of blood.

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39

Li, A. Dan. "Analysis of Polycyclic Aromatic Hydrocarbons Using Gas Chromatography-Mass Spectrometry with Multiphoton Ionization Technique." Advanced Materials Research 955-959 (June 2014): 1089–92. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.1089.

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Gas chromatography resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (GC/REMPI-TOFMS) using a nanosecond laser has been applied to analyze the 16 polycyclic aromatic hydrocarbons (PAHs). The excited-state lifetime, absorption characters, energy of electronic states of the 16 PAHs were investigated to optimize the ionization yield. The results suggested that REMPI is superior to elctron impact ionization method for soft ionization, and suppresses the background signal caused by the aliphatic hydrocarbons. Thus, GC/REMPI-TOFMS is a more reliable method for the determination of PAHs present in the environment.

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Курченко, Андрей. "MALDI MASS SPECTROMETRY - IN THE ASSESSMENT OF HUMAN MICROBIOTA. CURRENT STATE AND PERSPECTIVES." Immunology and Allergy: Science and Practice, no. 2 (July 29, 2020): 11–18. http://dx.doi.org/10.37321/immunology.2020.02-02.

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Mass spectrometry is a modern physicochemical method of analysis that allows for a qualitative and quantitative analysis of the composition of a substancebased on the preliminary ionization of its constituent atoms or molecules. One of the new methods of ionization, thanks to which the mass spectrometric study of macromolecules has become widespread, is matrix-activated laser desorption / ionization (MALDI), which is a pulsed laser irradiation of the substance under study mixed with a matrix.Тhe article presents modern data on the use of the MALDI mass- spectrometry method for conducting genus and species-specific identification of microorganisms in the practice of diagnostic laboratories. The advantages of MALDI-TOF identification in comparison with other methods of microbiota research are considered.The place of mass spectrometry in the system of laboratory diagnostics of various pathogens is indicated.

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Glushkov, O. V., O. Yu Khetselius, A. A. Kuznetsova, A. A. Svinarenko, and V. B. Ternovsky. "Advanced Laser-Photoionization Scheme of Separation of Heavy Isotopes in the Gases Separator Devices." Physics of aerodisperse systems, no. 59 (November 8, 2021): 173–83. http://dx.doi.org/10.18524/0367-1631.2021.59.227379.

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An effective approach to determining the parameters of the optimal schemes of the method of laser selective photoionization of atoms (elements and isotopes) with finite ionization due to collisions, ionization by a pulsed electric field, ionization through high (Rydberg) states and narrow autoionization resonances for the separation of heavy isotopes has been proposed. in gas separator devices. On the basis of the theory of optimal control and previously developed quantum models for calculating the characteristics of elementary atomic processes, optimization models of isotope separation are numerically implemented in the scheme of selective laser photoionization with ionization due to collisions in gas mixtures, ionization by a pulsed electric field, autoionization, etc. etc. The data obtained quantitatively confirm the promise of the method of laser photoionization with finite ionization due to collisions, ionization by a pulsed electric field, ionization through high-lying (Rydberg) states and narrow autoionization resonances and give a set of parameters for the desired optimal schemes, in particular, the laser pulse optimal shape for rubidium and uranium isotopes.

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Li, Min, Yong Zhang, Qian-Yu Zhang, et al. "An efficient method for producing ⁹Be⁺ ions using a 2 + 1 resonance-enhanced multiphoton ionization process." Journal of Physics B: Atomic, Molecular and Optical Physics 55, no. 3 (2022): 035002. http://dx.doi.org/10.1088/1361-6455/ac4c8f.

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Abstract We report a method of creating pure 9Be+ ions by a 2 + 1 resonance-enhanced multiphoton ionization for the ionization potential of 75 192.64(6) cm−1 (133 nm). The efficient generation of 9Be+ ions has been realized in a segmented linear ion trap. The average loading rates with a 10 ns, 1 mJ laser at 310 nm and 306 nm are 3.8 and 1.3 ions per pulse, respectively. This method has the advantage of reducing the electron contamination to the ion trap electrodes greatly. It also reduces the requirement of single-photon energy while satisfying the need for ionization probability and can be applied to other atoms with high ionization thresholds.

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Inutan, Ellen D., and Sarah Trimpin. "Matrix Assisted Ionization Vacuum (MAIV), a New Ionization Method for Biological Materials Analysis Using Mass Spectrometry." Molecular & Cellular Proteomics 12, no. 3 (2012): 792–96. http://dx.doi.org/10.1074/mcp.m112.023663.

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Coon, Joshua J., Kevin J. McHale, and W. W. Harrison. "Atmospheric pressure laser desorption/chemical ionization mass spectrometry: a new ionization method based on existing themes." Rapid Communications in Mass Spectrometry 16, no. 7 (2002): 681–85. http://dx.doi.org/10.1002/rcm.626.

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Xu, Yun, and Wolfgang Schrader. "Studying the Complexity of Biomass Derived Biofuels." Energies 14, no. 8 (2021): 2032. http://dx.doi.org/10.3390/en14082032.

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Biofuel produced from biomass pyrolysis is a good example of a highly complex mixture. Detailed understanding of its composition is a prerequisite for optimizing transformation processes and further upgrading conditions. The major challenge in understanding the composition of biofuel derived from biomass is the wide range of compounds with high diversity in polarity and abundance that can be present. In this work, a comprehensive analysis using mass spectrometry is reported. Different operation conditions are studied by utilizing multiple ionization methods (positive mode atmospheric pressure photo ionization (APPI), atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) and negative mode ESI) and applying different resolving power set-ups (120 k, 240 k, 480 k and 960 k) and scan techniques (full scan and spectral stitching method) to study the complexity of a pyrolysis biofuel. Using a mass resolution of 960 k and the spectral stitching scan technique gives a total of 21,703 assigned compositions for one ionization technique alone. The number of total compositions is significantly expanded by the combination of different ionization methods.

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Xiong, Caiqiao, Xiaoyu Zhou, Jianing Wang, et al. "Ambient Aerodynamic Desorption/Ionization Method for Microparticle Mass Measurement." Analytical Chemistry 85, no. 9 (2013): 4370–75. http://dx.doi.org/10.1021/ac303565a.

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Jano, I. "Approximate method for calculating the valance-shell ionization potentials." Journal de Chimie Physique 89 (1992): 915–30. http://dx.doi.org/10.1051/jcp/1992890915.

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Yun, Renjie, Edvardas Narevicius, and Vitali Averbukh. "Penning ionization widths by Fano-algebraic diagrammatic construction method." Journal of Chemical Physics 148, no. 11 (2018): 114101. http://dx.doi.org/10.1063/1.4999753.

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Arulsamy, Andrew Das. "Renormalization group method based on the ionization energy theory." Annals of Physics 326, no. 3 (2011): 541–65. http://dx.doi.org/10.1016/j.aop.2010.09.011.

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Mestechkin, M. M., V. N. Poltavets, and G. E. Vaiman. "Ionization potentials of alternant radicals in the ?SCF method." Journal of Structural Chemistry 31, no. 3 (1990): 480–81. http://dx.doi.org/10.1007/bf00743592.

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