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Mass Spectrometry

Tatsuro Shirota, Kennosuke Hoshina
A sheet-like ultraviolet (UV) probe laser is used to investigate the ejection and propagation of ion packets of matrix CHCA, which are produced by matrix-assisted laser desorption and ionization (MALDI). Laser irradiation of the expanding MALDI plume induced photodissociation of the CHCA-related ions, which existed in a sheet-like volume, leading to their absence in their MALDI signal profiles. The MALDI spectra were measured under varying conditions: the temporal delay of the lasers and the distance of the sheet-like probe laser from the MALDI sample surface...
2018: Mass Spectrometry
Shinichi Enami, Agustín J Colussi
Air pollutants generate reactive oxygen species on lung surfaces. Here we report how hydroxyl radicals (·OH) injected on the surface of water react with SP-B1-25 , a 25-residue polypeptide surrogate of human lung surfactant protein B. Our experiments consist of intersecting microjets of aqueous SP-B1-25 solutions with O3 /O2 /H2 O/N2 (g) gas streams that are photolyzed into ·OH(g) in situ by 266 nm laser nanosecond pulses. Surface-sensitive mass spectrometry enables us to monitor the prompt (<10 μs) and simultaneous formation of primary O n -containing products/intermediates ( n ≤5) triggered by the reaction of ·OH with interfacial SP-B1-25 ...
2018: Mass Spectrometry
Shoichiro Yokota
Isotope analyses using mass spectrometers have been frequently utilized in the laboratories for the earth planetary science and other scientific and industrial fields. In order to conduct in-situ measurements of compositions and isotope ratios around planets and moons, mass spectrometers onboard spacecraft have also been developed. Ion and electron instruments on orbiters have provided much outputs for the space and planetary science since the early days and mass spectrometers on landers and rovers have recently performed isotope analyses on planetary bodies...
2018: Mass Spectrometry
Yuko Nakashima, Mitsutoshi Setou
Oligonucleotide-based therapeutics such as antisense oligonucleotides, small interfering RNAs (siRNAs), decoy and aptamer have been extensively developed. To investigate the pharmacokinetics of oligonucleotide therapeutics, it is common to label a radioisotope in a nucleic acid and visualize it. However, if the labeled terminal nucleotide is decomposed by a nuclease in vivo , only the labeled nucleotide is detected, and it is impossible to observe the nucleic acid exhibiting the drug effect. The distribution of biomolecules, such as phospholipids, proteins, and glycolipids, can be obtained and visualized without labeling using matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS)...
2018: Mass Spectrometry
Satoshi Ninomiya, Yuji Sakai, Lee Chuin Chen, Kenzo Hiraoka
Atmospheric pressure electrospray had been used in previous studies to generate massive water droplet ion beams, and the beams successfully achieved efficient desorption/ionization of biomolecules, low damage etching of polymers and nonselective etching of metal oxides. However, this droplet ion beam was not practical as a primary ion beam for surface analysis instruments because it required differential pumping and lacked adequate beam current and density. To improve the beam performance, we have proposed to use vacuum electrospray of aqueous solutions as a beam source, and developed a technique for producing a stable electrospray of aqueous solution in vacuum...
2018: Mass Spectrometry
Jiying Pei, Ruiling Zhang, Chengchih Hsu, Yinghui Wang
2,6-Dichloro-1,4-benzoquinone (DCBQ), a highly toxic and carcinogenic disinfection by-product, was degraded during the electrospray process by elevating the source temperature. This unexpected finding inspired us to use heating to degrade DCBQs in drinking water. The results show that about 99% of DCBQs in the drinking water were degraded in one minute by heating to 100°C with room light irradiation. Therefore, a conclusion can be drawn that heating enables the degradation of DCBQs in drinking water.
2018: Mass Spectrometry
Chie Araki, Nobuyuki Okahashi, Kousuke Maeda, Hiroshi Shimizu, Fumio Matsuda
Cancer cells often respond to chemotherapeutic inhibitors by redirecting carbon flow in the central metabolism. To understand the metabolic redirections of inhibitor treatment on cancer cells, this study established a 13 C-metabolic flux analysis (13 C-MFA)-based method to evaluate metabolic redirection in MCF-7 breast cancer cells using mass spectrometry. A metabolic stationary state necessary for accurate 13 C-MFA was confirmed during an 8-24 h window using low-dose treatments of various metabolic inhibitors...
2018: Mass Spectrometry
Wataru Tanaka, Masanori Arita
Current bottleneck of comprehensive non-target metabolite identification is insufficient spectral library. Many research groups have tried to build a theoretical product ion spectral library independent of measurement condition or settings, but mechanisms of metabolite fragmentation are not fully clarified. To achieve the mechanistic prediction of metabolite fragmentation which covers a wide range of metabolites, we will discuss utilization of physicochemical calculation. We introduce bonding patterns, which include two bound atoms and chemical groups adjacent to the bond...
2018: Mass Spectrometry
Toshihiro Suzuki, Shuhei Sakata, Yoshiki Makino, Hideyuki Obayashi, Seiya Ohara, Kentaro Hattori, Takafumi Hirata
We report on the development of a software program named iQuant2 which creates visual images from two-dimensional signal intensity data obtained by a laser ablation-ICP-mass spectrometry (LA-ICPMS) technique. Time-resolved signal intensity profiles can be converted to position resolved signal intensity data based on the rastering rate (μm s-1 ) of the laser ablation. Background signal intensities obtained without laser ablation (gas blank) are used as the background, and all of the blank-subtracted intensity data can be used for the imaging analysis...
2018: Mass Spectrometry
Yoshiaki Nabuchi, Kenji Hirose, Mitsuo Takayama
Ion mobility experiments coupled with electrospray ionization (ESI) were conducted to evaluate the folding states of bovine carbonic anhydrase 2 (CA2) under three different pH conditions. Collision cross-section (CCS) of the CA2 ions generated by ESI revealed the presence of six discrete conformers in the gas phase under the conditions employed in this study. The CCS of the most extended conformer was three times larger than that of the most compact one. The charge state distribution of the CA2 ions was indicative of three conformers being present...
2018: Mass Spectrometry
Toshiki Sugai
The relationship between mass and charge has been a crucial topic in mass spectrometry (MS) because the mass itself is typically evaluated based on the m / z ratio. Despite the fact that this measurement is indirect, a precise mass can be obtained from the m / z value with a high m / z resolution up to 105 for samples in the low mass and low charge region under 10,000 Da and 20  e , respectively. However, the target of MS has recently been expanded to the very heavy region of Mega or Giga Da, which includes large particles and biocomplexes, with very large and widely distributed charge from kilo to Mega range...
2017: Mass Spectrometry
Mari Aida, Takahiro Iwai, Yuki Okamoto, Satoshi Kohno, Ken Kakegawa, Hidekazu Miyahara, Yasuo Seto, Akitoshi Okino
We developed a dual plasma desorption/ionization system using two plasmas for the semi-invasive analysis of compounds on heat-sensitive substrates such as skin. The first plasma was used for the desorption of the surface compounds, whereas the second was used for the ionization of the desorbed compounds. Using the two plasmas, each process can be optimized individually. A successful analysis of phenyl salicylate and 2-isopropylpyridine was achieved using the developed system. Furthermore, we showed that it was possible to detect the mass signals derived from a sample even at a distance 50 times greater than the distance from the position at which the samples were detached...
2017: Mass Spectrometry
Kenya Sakamoto, Kanako Sekimoto, Mitsuo Takayama
Hydrogen fluoride (HF) was produced by a homemade HF generator in order to investigate the properties of strong hydrogen-bonded clusters such as (HF) n . The HF molecules were ionized in the form of complex ions associated with the negative core ions Y(-) produced by atmospheric pressure corona discharge ionization (APCDI). The use of APCDI in combination with the homemade HF generator led to the formation of negative-ion HF clusters Y(-)(HF) n (Y=F, O2), where larger clusters with n≥4 were not detected. The mechanisms for the formation of the HF, F(-)(HF) n , and O2(-)(HF) n species were discussed from the standpoints of the HF generator and APCDI MS...
2017: Mass Spectrometry
Shigeo Hayakawa
High energy collision processes for singly charged positive ions using an alkali metal target are confirmed, as a charge inversion mass spectrometry, to occur by electron transfers in successive collisions and the dissociation processes involve the formation of energy-selected neutral species from near-resonant neutralization with alkali metal targets. A doubly charged thermometer molecule was made to collide with alkali metal targets to give singly and doubly charged positive ions. The internal energy resulting from the electron transfer with the alkali metal target was very narrow and centered at a particular energy...
2017: Mass Spectrometry
Tohru Yamagaki, Yasushi Makino
Six different sequences of hexasaccharides, pyridylaminated malto-hexaoses containing one N-acetyl hexosamine (HexNAc) residue, were analyzed using matrix-assisted laser desorption/ionization (MALDI) tandem time-of-flight (TOF) mass spectrometry (MS). Based on the product ion spectra of sodium adducts [M+Na](+), the chemical species of the observed product ions contained a HexNAc residue and had high ion abundance, indicating that the HexNAc residue had a higher affinity to sodium atom than glucopyranose. The acetamide group coordinated easily to sodium atom...
2017: Mass Spectrometry
Yin-Hung Lai, Yi-Sheng Wang
Although matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is one of the most widely used soft ionization methods for biomolecules, the lack of detailed understanding of ionization mechanisms restricts its application in the analysis of carbohydrates. Structural identification of carbohydrates achieved by MALDI mass spectrometry helps us to gain insights into biological functions and pathogenesis of disease. In this review, we highlight mechanistic details of MALDI, including both ionization and desorption...
2017: Mass Spectrometry
Akira Motoyama, Keishi Kihara
To provide safe and effective products to customers in the cosmetic industry, mass spectrometry (MS) is an indispensable analytical tool. In addition to its outstanding sensitivity and specificity, the method is applicable to a wide variety of compounds, which makes it irreplaceable for the development of cosmetics, which requires the analysis of complex systems. Because most cosmetic products are applied directly to the skin and function as they are designed, monitoring the molecular compositions of endogenous or exogenous compounds in or on the skin is crucial to ensure the safety and efficacy of a cosmetic product...
2017: Mass Spectrometry
Yukina Tatsuta, Yukie Tanaka, Akari Ikeda, Shigeru Matsukawa, Hajime Katano, Shu Taira
We compared two ionization methods, matrix assisted laser desorption/ionization (MALDI) and nanoparticle assisted laser desorption/ionization (Nano-PALDI) mass spectrometry (MS), for the analysis of amino acids derivatized with Py-Tag™ that consists pyrylium-based compound. Py-Tag is a useful stable derivatization reagent due to wide mass differences (using (13)C as the sole stable labelling isotope). For Py-Tag labelled lysine, sensitive signals that showed less noise with a ten times higher sensitivity, showed a wider mass difference by Nano-PALDI MS compared to MALDI MS...
2017: Mass Spectrometry
Tohru Yamagaki
No abstract text is available yet for this article.
2017: Mass Spectrometry
Lee Chuin Chen, Kentaro Yoshimura, Satoshi Ninomiya, Sen Takeda, Kenzo Hiraoka
In this paper, we briefly review the remote mass spectrometric techniques that are viable to perform "endoscopic mass spectrometry," i.e., in-situ and in-vivo MS analysis inside the cavity of human or animal body. We also report our experience with a moving string sampling probe for the remote sample collection and the transportation of adhered sample to an ion source near the mass spectrometer. With a miniaturization of the probe, the method described here has the potential to be fit directly into a medical endoscope...
2017: Mass Spectrometry
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