Offline two-dimensional liquid chromatography coupled with ion mobility-quadrupole time-of-flight mass spectrometry enabling fourdimensional separation and characterization of the multicomponents from white ginseng and red ginseng

Inherent complexity of plant metabolites necessitates the use of multi-dimensional information to accomplish comprehensive profiling and confirmative identification.A dimension-enhanced strategy,by offline two-dimensional liquid chromatography/ion mobility-quadrupole time-of-flight mass spectrometry(2 D-LC/IM-QTOF-MS)enabling four-dimensional separations(2 D-LC,IM,and MS),is proposed.In combination with in-house database-driven automated peak annotation,this strategy was utilized to characterize ginsenosides simultaneously from white ginseng(WG)and red ginseng(RG).An offline 2 DLC system configuring an Xbridge Amide column and an HSS T3 column showed orthogonality 0.76 in the resolution of ginsenosides.Ginsenoside analysis was performed by data-independent high-definition MSE(HDMSE)in the negative ESI mode on a Vion?IMS-QTOF hybrid high-resolution mass spectrometer,which could better resolve ginsenosides than MSEand directly give the CCS information.An in-house ginsenoside database recording 504 known ginsenosides and 58 reference compounds,was established to assist the identification of ginsenosides.Streamlined workflows,by applying UNIFI?to automatedly annotate the HDMSEdata,were proposed.We could separate and characterize 323 ginsenosides(including 286 from WG and 306 from RG),and 125 thereof may have not been isolated from the Panax genus.The established 2 D-LC/IM-QTOF-HDMSEapproach could also act as a magnifier to probe differentiated components between WG and RG.Compared with conventional approaches,this dimensionenhanced strategy could better resolve coeluting herbal components and more efficiently,more reliably identify the multicomponents,which,we believe,offers more possibilities for the systematic exposure and confirmative identification of plant metabolites.

Analyzing crude oils from the Junggar Basin(NW China) using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry(GC×GC-TOFMS)

As a new technology of analyzing crude oils,comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry(GC×GCTOFMS) has received much research attention.Here we present a case study in the Junggar Basin of NW China.Results show that the hydrocarbons,including saturates and aromatics,were all well-separated without large coelution,which cannot be realized by conventional one-dimensional GC-MS.The GC×GC technique is especially effective for analyzing aromatics and low-to-middlemolecular-weight hydrocarbons,such as diamondoids.The geochemical characteristics of crude oils in the study area were investigated through geochemical parameters extracted by GC×GC-TOFMS,improving upon the understanding obtained by GC-MS.Thus,the work here represents a new successful application of GC×GCTOFMS,showing its broad usefulness in petroleum geochemistry.

Dimension-Enhanced Ultra-High Performance Liquid Chromatography/Ion Mobility-Quadrupole Time-of-Flight Mass Spectrometry Combined with Intelligent Peak Annotation for the Rapid Characterization of the Multiple Components from Seeds of Descurainia sophia

The complex composition of herbal metabolites necessitates the development of powerful analytical techniques aimed to identify the bioactive components.The seeds of Descurainia sophia(SDS)are utilized in China as a cough and asthma relieving agent.Herein,a dimension-enhanced integral approach,by combining ultra-high performance liquid chromatography/ion mobility-quadrupole time-of-flight mass spectrometry(UHPLC/IMQTOF-MS)and intelligent peak annotation,was developed to rapidly characterize the multicomponents from SDS.Good chromatographic separation was achieved within 38 min on a UPLC CSH C18(2.1×100 mm,1.7μm)column which was eluted by 0.1%formic acid in water(water phase)and acetonitrile(organic phase).Collision-induced dissociation-MS^(2)data were acquired by the data-independent high-definition MS^(E)(HDMS^(E))in both the negative and positive electrospray ionization modes.A major components knockout strategy was applied to improve the characterization of those minor ingredients by enhancing the injection volume.Moreover,a self-built chemistry library was established,which could be matched by the UNIFI software enabling automatic peak annotation of the obtained HDMS^(E)data.As a result of applying the intelligent peak annotation workflows and further confirmation process,a total of 53 compounds were identified or tentatively characterized from the SDS,including 29 flavonoids,one uridine derivative,four glucosides,one lignin,one phenolic compound,and 17 others.Notably,four-dimensional information related to the structure(e.g.,retention time,collision cross section,MS^(1)and MS^(2)data)was obtained for each component by the developed integral approach,and the results would greatly benefit the quality control of SDS.

STRUCTURE EFFECTS OF SILICON AND CARBON BY CLUSTER MASS SPECTRA

Microclusters from different structures of silicon and carbon are studied by SIMS under UHV conditions in the mass range below M=200. The sputtered mass spectra of ions Sin+, Cn+ and Cn were obtained from the 10 keV O2+ primary beam bombardment. Comparisons of each spectrum in each group have shown the strong structure effects on the cluster patterns. A brief discussion on the results has been given.

An Explanation on the Electron Ionization Mass Spectra of Crown Ethers by MNDO Computational Method

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Quantum Chemistry Study on Structures of Cluster Ions Nb＿nS_ m~±Generated by Laser Mass Spectra

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Temporal and spatial study of differently charged ions emitted by ns-laser-produced tungsten plasmas using time-of-flight mass spectroscopy

Tungsten(W)is an important material in tokamak walls and divertors.The W ion charge state distribution and the dynamic behavior of ions play important roles in the investigation of plasma–wall interactions using laser-ablation-based diagnostics such as laser-induced breakdown spectroscopy and laser-induced ablation spectroscopy.In this work,we investigate the temporal and spatial evolutions of differently charged ions in a nanosecond-laser-produced W plasma in vacuum using time-of-flight mass spectroscopy.Ions with different charge states from 1 to 7(W+to W7+)are all observed.The temporal evolutions of the differently charged ions show that ions with higher charge states have higher velocities,indicating that space separation occurs between the differently charged ion groups.Spatially-resolved mass spectroscopy measurements further demonstrate the separation phenomenon.The temporal profile can be accurately fitted by a shifted Maxwell–Boltzmann distribution,and the velocities of the differently charged ions are also obtained from the fittings.It is found that the ion velocities increase continuously from the measured position of 0.75 cm to 2.25 cm away from the target surface,which indicates that the acceleration process lasts through the period of plasma expansion.The acceleration and space separation of the differently charged ions confirm that there is a dynamic plasma sheath in the laser-produced plasma,which provides essential information for the theoretical laser-ablation model with plasma formation and expansion.

THE MASS SPECTRA OF HKTEROCYCLIC CONJUGATED COMPOUND AND ITS QUANTUM CHEMICAL CALCULATIONS

A mechanism of cleft-rate-determining-step of furfurol,furylacrylic acid,dimethylfuran,thiophene-2-aldehyde,and pyrrole-2-aldehyde is.proposed,and various quantum parameters of molecular ions of these compounds and their fragments are calculated by using CNDO/2 method.The peak-height of mass spectra is quantitatively interpreted.This method could be extended to heterocyclic conjugated compounds.

The Development of Time-of-flight Mass Spectrometry( TOF-MS) and Its Applications in Screening Food Hazard Factors

The time-of-flight mass spectrometry(TOF-MS),one of the mass spectrometry techniques,has been widely applied in the field of rapid screening of food hazard factors as a superior analysis technique because of its wide mass range,high resolution and mass measurement accuracy,high sensitivity and high analysis speed.In this paper,research progresses of TOF-MS on the detection of food additives,food contaminants and residues,illegal additives,pesticide residues,veterinary drug residues and mycotoxin were reviewed,and its probable approaching applications were prospected.

MicrobMatcher: a microbial comparison software based on matrix-assisted laser desorption/ionization with time-of-flight mass spectrometry

Matrix-assisted Laser Desorption/Ionization with Time-of-flight Mass Spectrometry (MALDI-TOFMS) was investigated as a method for the rapid identifica-tion of species. Current demand in microbial identi-fication is how to compare unknown strains to the known one quickly, semi-automatically and accurately. In this paper, we present a software tool that allows flexibly microbial matching in a user-friendly way, by letting the users to customize comparison parameters including: in vitro transcription enzyme, mass tolerance,minimum fragment length, intensity threshold and corresponding weights. We provide three spectral scoring functions to compute the affin-ity between the species. Therefore, the precision of microbial comparison increases. To test and verify this tool, we employed experimental spectral data based on MALDI-TOFMS and the gene sequences of E.coli and Salmonella. This software is written in Java for cross-platform intention.

Application of Liquid Chromatography-High Resolution Time-of-flight Mass Spectrometry in the Detection of Raw Milk and Dairy Products

Milk and dairy products are more and more popular with consumers due to their various nutrients, and their quality and safety issues have always been concerned. Therefore, the development of rapid, accurate and simple screening techniques is of great significance. Liquid chromatography-high resolution time-of-flight mass spectrometry has high-resolution and high-throughput detection functions, and has gradually begun to be applied in the detection of milk and dairy products. This paper summarized the application of milk and dairy products in liquid chromatography-high resolution time-of-flight mass spectrometry, laying a foundation for the development of new methods.

5-22 Design and Optimization of a Multi-re Time-of-flight Mass Analyzer for LPT

Multi-reflection time-of-flight mass spectrometer (MR-TOF-MS) is one of the new experimental devices developed in recent years. As the flight path extended several orders of magnitude as the analyzer is traversed many times by the ions, it allows achieving higher mass resolving power than the conventional time-of-flight mass spectrometry.

Time-of-Flight Mass Spectrometer with Transaxial Ion Reflector

Two variants of application of a transaxial mirror with stigmatic spatial time-of-flight focusing in the time-of-flight mass spectrometer have been considered. In the first variant, the transaxial mirror is used as an ion reflector in the ordinary scheme of the time-of-flight mass reflectron. In the second variant, the transaxial mirror simultaneously fulfills the function of the ion reflector and corrector of aberrations caused by the energy spread of ions in the package, formed by the ion source of the mass reflectron. The expressions defining the conditions of stigmatic spatial time-of-flight focusing in the transaxial mirror and the combined system consisting of an ion source and a mirror have been derived. The relationships between geometrical and electrical parameters of three- and four-electrode transaxial mirrors realizing these conditions have been obtained by numerical calculations.

新型苯环己哌啶衍生物溴胺酮的表征与分析

为了对案件缴获的疑似毒品进行分析,确认化合物种类,建立化合物的表征数据,本文基于气相色谱–质谱联用技术(GC-MS)、液相色谱–高分辨飞行时间质谱联用技术(LC-QTOF)、傅里叶变换红外光谱技术(FT-IR)、核磁共振氢谱(1HNMR)及碳谱(13CNMR)、X射线单晶衍射(X-raydiffractionofsingle crystal)等多种手段对目标化合物进行分析和表征。测定了已列管的氯胺酮和氟胺酮的二级质谱,建立中性丢失质谱碎片信息,并与目标化合物进行比对。通过多种分析手段与中性丢失质谱碎片信息比对结果,确认该化合物为溴胺酮。新型苯环己哌啶衍生物溴胺酮存在一定的毒品替代和滥用风险,本研究建立的溴胺酮的分析与表征数据能够为公安机关对溴胺酮的鉴定工作提供参考依据。

HL-2A装置硅化镀膜壁处理控制杂质行为研究

硅化壁处理能有效控制等离子体杂质和再循环水平,是HL-2A装置的常规壁处理手段。介绍了HL-2A装置的硅化壁处理系统以及硅化镀膜壁处理控制杂质行为的主要研究进展。HL-2A装置硅化壁处理系统包括离线硅化和在线硅化壁处理系统,分别采用辉光放电辅助沉积以及等离子体放电辅助沉积进行硅化镀膜壁处理。实验结果表明,离线硅化壁处理后氧杂质明显降低,但随着实验进行会逐渐增加,硅化镀膜寿命约150炮。为进一步开展研究,HL-2A采用了在线硅化壁处理技术,研究发现在线硅化壁处理过程中碳、氧、铁等杂质均有所减少。两种硅化方式下真空室内的H_(2)O、CO含量均明显降低,在线硅化壁处理耗气量远少于离线硅化。通过硅化壁处理,有效地提升了HL-2A等离子体性能,也为未来聚变装置稳态运行器壁的处理提供了重要技术参考。

Electrostatic-lenses position-sensitive TOF MCP detector for beam diagnostics and new scheme for mass measurements at HIAF

A foil–microchannel plate(MCP)detector,which uses electrostatic lenses and possesses both good position and timing resolutions,has been designed and simulated for beam diagnostics and mass measurements at the next-generation heavy-ion-beam facility HIAF in China.Characterized by low energy loss and good performances of timing and position measurements,it would be located at focal planes in fragment separator HFRS for position monitoring,beam turning,Bq measurement,and trajectory reconstruction.Moreover,it will benefit the building-up of a magnetic-rigidity–energy-loss–time-offlight(BqDETOF)method at HFRS for high-precision in-flight particle identification of radioactive isotope beams on an event-by-event basis.Most importantly,the detector can be utilized for in-ring TOF and position measurements,beam-line TOF measurements at two achromatic foci,and position measurements at a dispersive focus of HFRS,thus making it possible to use two complementary mass measurement methods[isochronous mass spectrometry at the storage ring SRing and magnetic-rigidity–time-of-flight(BqTOF)at the beam-line HFRS]in one single experimental run.

Mass Spectrometric Study of Acetylated Glycopyranosyl Azides

Introduction Glycosyl azides are useful, versatile intermediates for the synthesis of N-glyeosyl derivatives and other biologically important non-carbohydrate derivatives since the azido group can be introduced readily into aliphatic, aromatic and heterocyclic systems, and can be transformed into other functional groups and utilized for the synthesis of hetero-

FAB MASS SPECTROMETRY OF THE PHENOLATEBRIDGED N_8O_3 SCHIFFBASE CRYPTANDS

The fast atom bobardment mass spectra of phenolate-bridged N8O3 Schiff-2base cryptands derived from tris （2-aminoethyl） amine （tren） with 2, 6-dlformyl-4-R-phenol （Cryptand H3L1, R=OMe） H3L3, Br, and H3L4, Ph) in the presence of NaOH or KON in methanol at ambient temperature was investigaed and compared with IR, UV-Vis, 1H and 13H NMR. The characteristic spectra of the cryptates posseessing different proton form cryptands were discussed.

Study of Non-Thermal DC Arc Plasma of CH_4/Ar at Atmospheric Pressure Using Optical Emission Spectroscopy and Mass Spectrometry

Non-thermal C/H/Ar plasmas are widely applied to carbonaceous material production and processing.In this work,plasma parameters and gaseous species of the atmospheric non-thermal C/H/Ar plasmas produced by an atmospheric-pressure DC arc discharge generator in CH_4/Ar were investigated.The voltage-current characteristics were measured for different CH_4/Ar ratios.Optical emission spectroscopy was employed to analyze the electron excitation temperature,gas temperature and electron density under various discharge conditions.The hydrocarbon molecules produced in the CH_4/Ar plasmas were detected with photoionization mass spectrometry.The optical spectral results demonstrated that the electron excitation temperature was 0.4-1 eV,the gas temperature was 2800-4200 K and the electron density was in the range of(5-20)×10^(15) cm^(-3).The mass spectrum indicated that a variety of unsaturated hydrocarbons(C_2H_4,C_3H_6,C_6H_6,etc.) and several highly unsaturated hydrocarbons(C_4H_2,C_5H_6,etc.) were produced in the non-thermal arc plasmas.

Plasma Immersion Ion Implantation of the Pea Seed and Its RBS Spectra

Plasma immersion ion implantation (PI^3), a new technique with certain advantages over biological samples, was developed. Argonion as well as nitrogen ion implantation of the pea seeds has been carried out with the PI^3 implanter and their RBS spectra were also studied. The results show that the mass deposition effect of ion implantation on biological samples can be achieved with the PI^3 implanter. In addition, there is an optimal implantation time for a given treatment condition. It presents new possibilities for the ion implantation into biological samples.