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Kenzo Hiraoka, Yuji Sakai, Hiroyuki Kubota, Satoshi Ninomiya, Stephani ...
2023 年 12 巻 1 号 p.
A0114
発行日: 2023/01/31
公開日: 2023/01/31
[早期公開] 公開日: 2022/12/24
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Among the various types of cluster secondary ion mass spectrometry (SIMS), electrospray droplet impact/secondary ion mass spectrometry (EDI/SIMS) is unique due to its high ionization efficiency and non-selective atomic/molecular-level surface etching ability. In this study, EDI/SIMS was applied to the non-selective etching of synthetic polymers of polystyrene (PS) and poly(9,9-di-n-octylfluonyl-2,7diyl) (PFO) deposited on a silicon substrate. The polymers gave characteristic fragment ions and the mass spectra remained unchanged with prolonged EDI irradiation time, indicating that non-selective etching can be achieved by EDI irradiation, a finding that is consistent with our previous reports based on EDI/X-ray photoelectron spectroscopy analyses. From the irradiation time and film thickness, the etching rates for PS and PFO were roughly estimated to be 0.6 nm/min and 0.15 nm/min, respectively, under the experimental conditions that were used. After the depletion of polymer sample on the surface, ion signals originating from the exposed silicon substrate were observed. This indicates that EDI/SIMS is applicable to the analysis of the interface of multilayered films composed of organic and inorganic materials.
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Narumi Moromoto, Yosuke Kawai, Kentaro Terada, Masaaki Miyahara, Naoto ...
2023 年 12 巻 1 号 p.
A0115
発行日: 2023/02/10
公開日: 2023/02/10
[早期公開] 公開日: 2023/01/13
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Northwest Africa (NWA) 2977 is a lunar basaltic meteorite that was found in 2005 and has been classified as an olivine cumulate gabbro. This meteorite contains a shock melt vein (SMV) induced by an intense shock event. We report herein on an in-situ analysis of phosphates in the host gabbro and the shock vein for the U–Pb dating of NWA 2977 using an ion microprobe, NanoSIMS. The majority of the analyzed phosphates, in both the SMV and host-rock, lie on a linear regression in 238U/206Pb–207Pb/206Pb–204Pb/206Pb three-dimensional space, indicating a total Pb/U isochron age of 3.15±0.12 Ga (95% confidence level), which is consistent ages determined in previous isotopic studies of NWA 2977 (Sm–Nd age of 3.10±0.05 Ga, Rb–Sr age of 3.29±0.11 Ga, and Pb–Pb baddeleyite age of 3.12±0.01 Ga), and identical to the age of the U–Pb phosphate in a paired meteorite NWA 773, 3.09±0.20 Ga, derived from our dataset. There was no clear difference in the formation age between the phosphates found in the SMV and host-rock, although the shape and size of the grains and the Raman spectra show the evidence of intense shock metamorphism. Based on these findings, the cooling rate of the phosphate was very rapid, constrained to be larger than 140 K/s.
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Shuji Yamashita, Takafumi Hirata
2023 年 12 巻 1 号 p.
A0116
発行日: 2023/04/06
公開日: 2023/04/06
[早期公開] 公開日: 2023/03/08
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Single particle inductively coupled plasma mass spectrometry combined with the laser ablation technique (LA-spICP-MS) has been used for the determination of particle size and the spatial distribution of metal nanoparticles (MNPs) in various solid samples such as biological samples and semiconductor materials. In this study, we investigated the effect of the fluence of the laser being used on the disintegration of MNPs. Commercially available MNPs of silver and gold (Ag NPs and Au NPs), the sizes of which were determined by transmission electron microscopy (TEM), were analyzed with LA-spICP-MS. We evaluated the degree of disintegration of the original-sized particles, based on a comparison of the size distributions obtained by LA-spICP-MS and other analytical techniques. The disintegration of both the Ag NPs and Au NPs was induced by a laser ablation process when the laser fluence was higher than 1.0 J cm−2, whereas no disintegration was observed when the fluence was lower than 1.0 J cm−2. Moreover, the mean diameter and standard deviation of the determined diameters obtained by LA-spICP-MS were in good agreement with solution-based spICP-MS and TEM analysis within analytical uncertainty. The data obtained here demonstrates that LA-spICP-MS represents a promising potential analytical technique for accurately determining the size of individual MNPs and their spatial distribution in solid samples.
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Daisuke Takakura, Haruka Yoshida, Shoko Ohashi, Nana Kawasaki
2023 年 12 巻 1 号 p.
A0117
発行日: 2023/04/11
公開日: 2023/04/11
[早期公開] 公開日: 2023/03/15
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Aberrant glycosylation of membrane proteins is a hallmark of cancer and a useful molecular marker for the diagnosis of breast cancer (BC). However, the molecular mechanisms by which altered glycosylation affects the malignant transformations associated with BC are poorly understood. Accordingly, we performed comparative membrane N-glycoproteomics using the human BC cell line pair, Hs578T, and its syngeneic normal cell line, Hs578Bst. A total of 359 N-glycoforms derived from 113 proteins were identified in both cell lines, of which 27 were found only in Hs578T cells. Significant changes in N-glycosylation were found in the lysosome-associated membrane protein 1 (LAMP1), the integrin family, and laminin. Confocal immunofluorescence microscopy images revealed the accumulation of lysosomes in the perinuclear space in cancer cells, which could be associated with marked changes in LAMP1 glycosylation, such as a decreased level of polylactosamine chains. Overall, the alterations in glycosylation may be involved in changes in the adhesion and degradation of BC cells.
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Mark Beattie, Oliver A. H. Jones
2023 年 12 巻 1 号 p.
A0118
発行日: 2023/04/06
公開日: 2023/04/06
[早期公開] 公開日: 2023/03/14
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Mass spectrometry is a well-established analytical technique for studying the masses of atoms, molecules, or fragments of molecules. One of the key metrics of mass spectrometers is the limit of detection e.g., the minimum amount of signal from an analyte that can be reliably distinguished from noise. Detection limits have improved greatly over the last 30–40 years to the point that nanogram per litre and even picogram per litre detections are commonly reported. There is however, a difference between detection limits obtained with a single, pure compound in a pure solvent and those obtained from real life samples/matrixes. Determining a practical detection limit for mass spectrometry is difficult because it depends on multiple factors, such as the compound under test, the matrix, data processing methods and spectrometer type. Here we show the improvements in reported limits of detection on mass spectrometers over time using industry and literature data. The limit of detection for glycine and dichlorodiphenyltrichloroethane were taken from multiple published articles spanning a period of 45 years. The limits of detection were plotted against the article’s year of publication to assess whether the trend in improvement in sensitivity resembles Moore’s Law of computing (essentially doubling every two years). The results show that advancements in detection limits in mass spectrometry are close to, but not quite at a rate equivalent to Moore’s Law and the improvements in detection limits reported from industry seem to be greater than those reported in the academic literature.
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Yamato Miyazaki, Atsushi Yamamoto
2023 年 12 巻 1 号 p.
A0119
発行日: 2023/04/06
公開日: 2023/04/06
[早期公開] 公開日: 2023/03/21
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To evaluate the safety of food for pets, the migration of chemical substances from pet tableware was investigated by mass spectrometry. The presence of polymer additives Irgafos 168 and Erucamide were suspected based on mass spectra and were confirmed to be present in polypropylene tableware. The amount of substances migrated using simulated saliva was examined by liquid chromatography-mass spectrometry after solid phase extraction and purification. Photoionization was found to be suitable for the simultaneous determination of these substances. The detection limits of the established method were 0.019 μg/mL for Irgafos 168 and 0.022 μg/mL for Erucamide. Five different types of pet tableware purchased in local markets were examined and no analytes were detected in the simulated saliva using shaking extraction. In this study, the risk to pets from the substances migrated from pet tableware was considered to be sufficiently low.
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Ayumi Kubo, Azusa Kubota, Haruki Ishioka, Takuhiro Hizume, Masaaki Ubu ...
2023 年 12 巻 1 号 p.
A0120
発行日: 2023/04/13
公開日: 2023/04/13
[早期公開] 公開日: 2023/03/21
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Electron ionization (EI) mass spectrum library searching is usually performed to identify a compound in gas chromatography/mass spectrometry. However, compounds whose EI mass spectra are registered in the library are still limited compared to the popular compound databases. This means that there are compounds that cannot be identified by conventional library searching but also may result in false positives. In this report, we report on the development of a machine learning model, which was trained using chemical formulae and EI mass spectra, that can predict the EI mass spectrum from the chemical structure. It allowed us to create a predicted EI mass spectrum database with predicted EI mass spectra for 100 million compounds in PubChem. We also propose a method for improving library searching time and accuracy that includes an extensive mass spectrum library.
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Takafumi Hirata, Menghao Yang, Hui Hsin Khoo
2023 年 12 巻 1 号 p.
A0121
発行日: 2023/05/11
公開日: 2023/05/11
[早期公開] 公開日: 2023/03/25
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In situ and rapid analysis of organic compounds using a combination of a newly-developed laser ablation in liquid (LAL) sampling technique combined with electrospray ionisation mass spectrometry (ESI-MS) is reported. The LAL is a technique that allows laser ablation to be conducted in a liquid medium containing organic compounds that were effectively extracted from solid materials into the liquid medium. Three organic compounds (valine, caffeine, and benzyl butyl phthalate (BBP)) were subjected to analysis. The LAL sampling was conducted in the fast-laser scanning mode using Galvanometric optics, and the total ablation time required for the sampling from a 1 mm2 area was about 3 s, thus providing rapid sampling. The resulting sample solution was directly introduced into the ESI-MS system, without the need for any chromatographic separation. To evaluate the analytical capability of the LAL technique coupled with ESI-MS, both the overall transmission efficiencies of analytes from solid materials to the ion detector, and the repeatabilities of the measurements were rigorously tested. This involved the use of synthetic, in-house prepared standard materials containing the analytes. The overall ion yields were about 1.1×10−3% for valine, 8.7×10−3% for caffeine, and 6.7×10−4% for BBP. By comparing the ion yields obtained by the injection of an analyte solution and a standard solution through the mass spectrometer, the recoveries through the LAL sampling were approximately 31% for valine, 45% for caffeine, and 37% for BBP. In addition, the analytical repeatabilities for all analytes were better than 6%. The analytical repeatabilities were mainly affected by either the heterogeneity of the in-house standard materials or changes in the plasma temperature by coexisting, laser-induced sample particles. It should be noted that not only water-soluble compounds (caffeine and valine), but also non-soluble compound (BBP) could be measured by the LAL-ESI-MS, which is one of the great advantages over the conventional liquid extraction surface analysis technique. The data obtained here clearly demonstrate that the LAL-ESI-MS has the potential for being a fast and user-friendly analytical technique for the in-situ detection for both the water-soluble and water-insoluble molecules.
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Shiho Fujishima, Kanako Sekimoto, Mitsuo Takayama
2023 年 12 巻 1 号 p.
A0124
発行日: 2023/06/21
公開日: 2023/06/22
[早期公開] 公開日: 2023/06/15
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The negative ion at m/z 20 observed at atmospheric pressure corona discharge ionization mass spectra has been identified by supplying the vapors of deuterium oxide (D2O) and H218O. From the mass shifts of the ion at m/z 20 observed with D2O and H218O, it was suggested that the chemical composition of the ion at m/z 20 is to be H4O. Further mass shift from m/z 20 to 22 was observed by supplying the vapor of perfluorokerocene, suggesting the chemical composition of H3F. The chemical compositions of the negative ions H4O− and H3F− were consistence with the dipole-bound complex states between hydrogen H2 and polar molecules such as H2O and hydrogen fluoride (HF) having dipole moments beyond a critical dipole moment of 1.625 D, theoretically proposed by Skurski and Simons. The ionic chemical compositions and structures of H4O− and H3F− obtained with density functional theory calculations implied that both dipole-bound complex H2O−…H2 and HF−…H2 can be formed by exothermic reactions by which H2 molecule is complexing with negative ions H2O− and HF−, respectively.
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Raju Bandu, Hyun Jeong Lee, Hyeong Min Lee, Tae Hyon Ha, Heon-Jeong Le ...
2023 年 12 巻 1 号 p.
A0123
発行日: 2023/07/06
公開日: 2023/07/06
[早期公開] 公開日: 2023/06/01
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Liquid chromatography/electrospray ionization-mass spectrometry revealed plasma metabolic profiles for the antidepressant drug escitalopram (ECTP) and associated clinical responses in subjects with major depressive disorder (MDD). Metabolic profiles contribute to variations in responses to drug treatment of depression. To assess clinical responses and treatment outcomes, we quantified the levels of metabolites, including those of the parent drug, in plasma samples collected at different time points (days 0, 7, 14, and 42) during treatment of seven patients with MDD. Results showed that mean plasma levels of key metabolites and ECTP at day 7 were significantly associated with the clinical response at 42 days after treatment. Statistical analyses, including principal component analysis, of key metabolites and ECTP samples at different time points clearly distinguished the clinical responders from non-responder subjects. Although further validation with a larger cohort is necessary, our results indicate that early improvement and plasma levels of key metabolites and ECTP are predictive of therapeutic treatment outcomes and thus can be used to guide the use of ECTP.
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Toshihiro Suzuki, Hui Hsin Khoo, Takafumi Hirata
2023 年 12 巻 1 号 p.
A0125
発行日: 2023/07/06
公開日: 2023/07/06
[早期公開] 公開日: 2023/06/28
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Simultaneous imaging analysis for both elements and molecules was conducted by introducing laser-induced sample particles into two separate mass spectrometers (i.e., an inorganic spectrometer and an organic mass spectrometer) through the split-flow protocol. The timing of ion detections for elements and molecules can be different, reflecting the differences in mass scan rates, lengths for transport tubing, and flow rates of carrier gases, and thus, the timing of ion detections must be carefully aligned to discuss abundance correlations between elements and molecules. To achieve this, a new data processing software “BioQuant” was developed to correct the time difference of the signal intensities for components obtained by the two mass spectrometers. With the BioQuant software, signal intensity data obtained from several unit cells were merged into a newly defined unit cell, calculated by the common time intervals from both mass spectrometers. With the newly defined unit cells, correlation analysis between the elements and molecules can be conducted. Combination of the BioQuant software and laser ablation system connected to two separated mass spectrometers can become a benchmark technique for simultaneous imaging analysis for both the elements and molecules from single sample material.
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Takehito Sagawa, Motoshi Sakakura
2023 年 12 巻 1 号 p.
A0126
発行日: 2023/07/06
公開日: 2023/07/06
[早期公開] 公開日: 2023/06/28
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“Retronasal aroma” refers to the aroma released from food during consumption and traveling through the nose after leaving the mouth. It is closely related to the behavior of odor compounds released from food into the mouth and plays a crucial role in our overall perception of flavor. As a result, research focusing on measuring the behavior of retronasal aroma has gained attention for exploring the relationship between sensory perception and flavor. We attempted to develop a data analysis method that specifically targets a time span of a few seconds to tens of seconds, starting from when food is placed in the mouth during eating and extending to just after swallowing. In this study, we observed a strong correlation between the periodic waveform data derived from performing the third derivative (jerk) on the detection intensity data obtained using a mass spectrometer and the behavior of the detection intensity. Furthermore, by performing a frequency analysis using a fast Fourier transform on the jerk data, it was possible to extract the frequencies that contribute to sensory perception during eating. Furthermore, the reconstructed jerk data derived from the extracted data using the inverse fast Fourier transform provided a clearer explanation of sensory perception during eating. Our algorithm suggests new short-term time-series data applications.
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Yuto Nishikido, Kanako Sekimoto
2023 年 12 巻 1 号 p.
A0127
発行日: 2023/07/29
公開日: 2023/07/29
[早期公開] 公開日: 2023/07/14
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J-STAGE Data
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The ionization and fragmentation patterns of 24 compounds with elemental composition of CmH2mO2, including isomeric esters and alkanoic acids, were investigated by atmospheric pressure corona discharge ionization collision-induced dissociation (CID) mass spectrometry in the positive-ion mode. All compounds were ionized as protonated molecules and NH4+ adducts. In addition, fragment ions were observed in mass spectra of esters other than methyl esters, which are owing to the dissociation of the alkyl group in the alcohol side from the protonated molecules. In CID spectra, protonated alkanoic acids/methyl esters split off H2O/CH3OH and CO or the alkyl group in the acid side, depending on the carbon chain length. Protonated esters (other than methyl esters) mainly fragmented the alkyl group in the alcohol side. These general rules on ionization and fragmentation patterns can provide relevant information on the discrimination of isomers.
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Kosei Kitagawa, Akimasa Fujihara, Tomoyuki Yatsuhashi
2023 年 12 巻 1 号 p.
A0130
発行日: 2023/10/03
公開日: 2023/10/03
[早期公開] 公開日: 2023/09/27
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Femtosecond laser ionization is a unique means to produce multiply charged organic molecules in the gas phase. The charge-dependent chemical reactions of such electron-deficient molecules are interesting from both fundamental and applied scientific perspectives. We have reported the production of quadruply charged perfluoroaromatics; however, they were so stable that we cannot obtain information about their chemical reactions. In general, it might be difficult to realize the conflicting objectives of observing multiply charged molecular ion themselves and their metastable dissociations. In this study, we report the first example showing metastable dissociations of several charge states within the measurable time range of a time-of-flight mass spectrometer. Metastable dissociations were analyzed by selecting a precursor ion with a Bradbury–Nielsen ion gate followed by time-of-flight analysis using a reflectron. We obtained qualitative information that triply and quadruply charged decafluorobiphenyl survived at least in the acceleration region but completely decomposed before entering a reflectron. In contrast, three dissociation channels for singly and one for doubly charged molecular ions were discriminated by a reflectron and determined with the help of ion trajectory simulations.
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Shuichi Shimma, Hiromi Saito, Takuya Inoue, Fukumatsu Iwahashi
2023 年 12 巻 1 号 p.
A0132
発行日: 2023/10/12
公開日: 2023/10/12
[早期公開] 公開日: 2023/09/28
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Pesticide seed treatment provides efficient crop protection in the early season and enables a reduction in the quantity of fungicides used later. Hence, it has been a practical application for crop protection in major crop sectors such as corn, soybean, wheat, and cotton. The chemicals on pesticide-treated seeds may show different distributions depending on the structure of the seeds and the physical properties of the chemicals, but they have not been well studied because of a lack of versatile analytical tools. Here, we used mass spectrometry imaging to visualize the distribution of a fungicide (ethaboxam) in corn and soybean seeds coated with it. Contrasting distribution patterns were noted, which are likely dependent on the seed structure. We also obtained information on fungicide distribution after the seedings, which will contribute to a better understanding of the fungicide delivery pathway within plants. Using this new analytical method, we were able to obtain hitherto unavailable time-dependent, dynamic information on the ethaboxam. We expect that this method will be a useful tool with widespread applications in pesticide development and use.
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Kazumi Saikusa, Daiki Asakawa, Sotaro Fuchigami, Satoko Akashi
2023 年 12 巻 1 号 p.
A0131
発行日: 2023/10/17
公開日: 2023/10/17
[早期公開] 公開日: 2023/09/29
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Ion mobility spectrometry–mass spectrometry (IMS-MS) provides m/z values and collision cross sections (CCSs) of gas-phase ions. In our previous study, an intrinsically disordered protein, the H2A-H2B dimer, was analyzed using IMS-MS, resulting in two conformational populations of CCS. Based on experimental and theoretical approaches, this resulted from a structural diversity of intrinsically disordered regions. We predicted that this phenomenon is related to ion heating in the IMS-MS instrument. In this study, to reveal the effect of ion heating from parameters in the IMS-MS instrument on the conformational population of the H2A-H2B dimer, we investigated the arrival time distributions of the H2A-H2B dimer by changing values of three instrumental parameters, namely, cone voltage located in the first vacuum chamber, trap collision energy (trap CE) for tandem mass spectrometry, and trap bias voltage for the entrance of IMS. These results revealed that the two populations observed for the H2A-H2B dimer were due to the trap bias voltage. Furthermore, to evaluate the internal energies of the analyte ions with respect to each parameter, benzylpyridinium derivatives were used as temperature-sensitive probes. The results showed that the trap CE voltage imparts greater internal energy to the ions than the trap bias voltage. In addition, this slight change in the internal energy caused by the trap bias voltage resulted in the structural diversity of the H2A-H2B dimer. Therefore, the trap bias voltage should be set with attention to the properties of the analytes, even if the effect of the trap bias voltage on the internal energy is negligible.
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Hiroshi Kobayashi, Toshinobu Hondo, Yasuo Kanematsu, Motohiro Suyama, ...
2023 年 12 巻 1 号 p.
A0134
発行日: 2023/11/07
公開日: 2023/11/07
[早期公開] 公開日: 2023/10/28
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The gain of the microchannel plate temporally drops after an ion initiates an electron avalanche. Electron multiplication was expected to deplete the charge from the microchannel wall and produce the depleted charge (wall charge). Moreover, it was reported that the gain drop occurred not only in the activated channels, where the electrons are multiplied, but also in the surrounding channels. One mechanism of the gain-drop spatial extension has been considered as that the wall charges in the activated channels change the electric field in the surrounding channels. Anacker et al. assumed that the wall charge is a uniform line charge; the gain-drop spatial extent should be proportional to the amount of the wall charges. We considered that the wall charges exponentially increased in the channel toward the exit. In this study, the electric field produced by the wall charges was calculated, considering the distribution of the wall charges. The transverse electric field generated by the wall charges was expected to disturb the electron trajectory near the channel exit and decrease the number of secondary electrons emitted per collision (gain per collision), resulting in a gain drop. The gain per collision was calculated to decrease by 22% for the position where the gain decreased significantly in the presence of the transverse electric field of 3×105 V/m. In our model, the gain-drop spatial extent extended proportionally to the square root of the wall charges when the distance from the activated channel exceeded 50 μm.
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Riko Takata, Yuji Nakabayashi, Kotaro Hashimoto, Akio Miyazato, Issey ...
2023 年 12 巻 1 号 p.
A0135
発行日: 2023/11/25
公開日: 2023/11/25
[早期公開] 公開日: 2023/11/09
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Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) has been widely used for analyses of biomolecules and industrial materials. Surface-assisted laser desorption/ionization (SALDI) is studied to complement the ionization ability for the MALDI/MS. In this study, lab-made mist chemical vapor deposition (mist CVD) system was used to produce metal films as ionization assistance materials for SALDI/MS. The system could give Ag film from inexpensive silver trifluoroacetate solution rapidly and simply under atmospheric pressure. Phosphatidylcholines could be detected high sensitively and diacylglycerols (DAGs) could not be detected in MALDI/MS. In the SALDI/MS and the MS imaging with Ag film by mist CVD, both the phosphatidylcholines and the DAGs could be detected and the localized images. In the Ag film-SALDI/MS of lipids, not only Ag-adducted ions but also Na- and K-adducted ions were detected. The Ag film formed by the mist CVD to act as an ionization-assistance material and a cationization agent in SALDI would be useful in MS imaging of biological tissue sections.
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Fumio Matsuda
2023 年 12 巻 1 号 p.
A0138
発行日: 2023/12/08
公開日: 2023/12/08
[早期公開] 公開日: 2023/11/30
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Non-targeted metabolome analysis studies comprehensively acquire product ion spectra from the observed ions by the data-dependent acquisition (DDA) mode of tandem mass spectrometry (MS). A DDA dataset redundantly contains closely similar product ion spectra of metabolites commonly existing among the biological samples analyzed in a metabolome study. Moreover, a single DDA data file often includes two or more closely similar raw spectra obtained from an identical precursor ion. The redundancy of product ion spectra has been used to generate an averaged product ion spectrum from a set of similar product ion spectra recorded in a DDA dataset. The spectral averaging improved the accuracy of m/z values and signal-to-noise levels of product ion spectra. However, the origins of redundancy, variations among datasets, and these effects on the spectral averaging procedure needed to be better characterized. This study investigated the nature of the redundancy by comparing the averaging results of eight DDA datasets of non-targeted metabolomics studies. The comparison revealed a significant variation in redundancy among datasets. The DDA datasets obtained by the quadrupole (Q)-Orbitrap-MS datasets had more significant intrafile redundancy than that of the Q-time-of-flight-MS. For evaluating the similarity score between two product ion spectra, the optimal threshold level of the cosine-product method was approximately 0.8–0.9. Moreover, contamination of biological samples such as plasticizers was another origin of spectral redundancy. The results will be the basis for further development of methods for processing of product ion spectra data.
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