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The“depict”strategy for discovering new compounds in complex matrices:Lycibarbarspermidines as a case
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作者 Chen Han Zhixin Zhang +8 位作者 Zhiyang Feng Chuanjia Zhai Xuejiao Li Yulian Shi Xiang Li Miao Li Ying Wang Gan Luo Xiaoyan Gao 《Journal of Pharmaceutical Analysis》 SCIE CAS CSCD 2024年第3期416-426,共11页
The comprehensive detection and identification of active ingredients in complex matrices is a crucial challenge.Liquid chromatography coupled with high-resolution mass spectrometry(LC-HRMS)is the most prominent analyt... The comprehensive detection and identification of active ingredients in complex matrices is a crucial challenge.Liquid chromatography coupled with high-resolution mass spectrometry(LC-HRMS)is the most prominent analytical platform for the exploration of novel active compounds from complex matrices.However,the LC-HRMS-based analysis workflow suffers from several bottleneck issues,such as trace content of target compounds,limited acquisition for fragment information,and uncertainty in interpreting relevant MS2 spectra.Lycibarbarspermidines are vital antioxidant active ingredients in Lycii Fructus,while the reported structures are merely focused on dicaffeoylspermidines due to their low content.To comprehensively detect the new structures of lycibarbarspermidine derivatives,a“depict”strategy was developed in this study.First,potential new lycibarbarspermidine derivatives were designed according to the biosynthetic pathway,and a comprehensive database was established,which enlarged the coverage of lycibarbarspermidine derivatives.Second,the polarity-oriented sample preparation of potential new compounds increased the concentration of the target compounds.Third,the construction of the molecular network based on the fragmentation pathway of lycibarbarspermidine derivatives broadened the comprehensiveness of identification.Finally,the weak response signals were captured by data-dependent scanning(DDA)followed by parallel reaction monitoring(PRM),and the efficiency of acquiring MS2 fragment ions of target compounds was significantly improved.Based on the integrated strategy above,210 lycibarbarspermidine derivatives were detected and identified from Lycii Fructus,and in particular,170 potential new compounds were structurally characterized.The integrated strategy improved the sensitivity of detection and the coverage of low-response components,and it is expected to be a promising pipeline for discovering new compounds. 展开更多
关键词 Mass spectrometric detection Weak response signals Complex matrices Novel lycibarbarspermidines
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Detailed analysis and simulation verification for reconstruction of plasma optical boundary with spectrometric technique on HL-2M tokamak 被引量:1
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作者 苏祉豪 高金明 高喆 《Plasma Science and Technology》 SCIE EI CAS CSCD 2023年第7期25-34,共10页
The plasma optical boundary reconstruction technique based on Hommen's theory is promising for future tokamaks with high parameters. In this work, we conduct detailed analysis and simulation verification to estima... The plasma optical boundary reconstruction technique based on Hommen's theory is promising for future tokamaks with high parameters. In this work, we conduct detailed analysis and simulation verification to estimate the ‘logic loophole' of this technique. The finite-width effect and unpredictable errors reduce the technique's reliability, which leads to this loophole. Based on imaging theory, the photos of a virtual camera are simulated by integrating the assumed luminous intensity of plasma. Based on Hommen's theory, the plasma optical boundary is reconstructed from the photos. Comparing the reconstructed boundary with the one assumed, the logic loophole and its two effects are quantitatively estimated. The finite-width effect is related to the equivalent thickness of the luminous layer, which is generally about 2-4 cm but sometimes larger. The level of unpredictable errors is around 0.65 cm. The technique based on Hommen's theory is generally reliable, but finite-width effect and unpredictable errors have to be taken into consideration in some scenarios. The parameters of HL-2M are applied in this work. 展开更多
关键词 Hommen's theory simulation verification finite-width effect unpredictable errors spectrometric technique plasma boundary identification system HL-2M tokamak plasma boundary reconstruction
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GCMS法测定番茄中的邻苯二甲酸酯类化合物 被引量:6
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作者 贝峰 左一鸣 +1 位作者 王超 聂梅 《食品研究与开发》 CAS 北大核心 2013年第23期101-103,共3页
为了解塑膜袋中的PAEs对番茄的污染程度。以套塑膜袋番茄为试材,采用GC-MS法测定番茄皮和番茄肉中的11种PAEs化合物。结果表明,套塑膜袋番茄皮中检出6种PAEs,浓度在0~2.70 mg/kg范围内;茄肉中含有4种PAEs,浓度在0~0.04 mg/kg之间... 为了解塑膜袋中的PAEs对番茄的污染程度。以套塑膜袋番茄为试材,采用GC-MS法测定番茄皮和番茄肉中的11种PAEs化合物。结果表明,套塑膜袋番茄皮中检出6种PAEs,浓度在0~2.70 mg/kg范围内;茄肉中含有4种PAEs,浓度在0~0.04 mg/kg之间。套纸膜复合袋番茄皮中检出5种PAEs,含量在0~5.17 mg/kg之间;茄肉中检出2种PAEs,浓度为0~0.07 mg/kg。可见塑膜袋中的PAEs对番茄有一定污染,主要富集于番茄皮部分,番茄肉中PAEs浓度较低。 展开更多
关键词 气相色谱-质谱 塑膜袋 番茄 邻苯二甲酸酯类化合物 gas chromatography-mass spectrometric(GC-MS)
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Product Identification and Mass Spectrometric Analysis of n-Butane and i-Butane Pyrolysis at Low Pressure 被引量:1
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作者 张义军 苑文浩 +3 位作者 蔡江淮 张李东 齐飞 李玉阳 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2013年第2期151-156,I0003,共7页
The pyrolysis of n-butane and i-butane at low pressure was investigated from 823-1823 K in an electrically heated flow reactor using synchrotron vacuum ultraviolet photoionization mass spectrometry. More than 20 speci... The pyrolysis of n-butane and i-butane at low pressure was investigated from 823-1823 K in an electrically heated flow reactor using synchrotron vacuum ultraviolet photoionization mass spectrometry. More than 20 species, especially several radicals and isomers, were detected and identified from the measurements of photoionization efficiency (PIE) spectra. Based on the mass spectrometric analysis, the characteristics of n-butane and i-butane pyrolysis were discussed, which provided experimental evidences for the discussion of decomposition pathways of butane isomers. It is concluded that the isomeric structures of n-butane and i-butane have strong influence on their main decomposition pathways, and lead to dramatic differences in their mass spectra and PIE spectra such as the different dominant products and isomeric structures of butene products. Furthermore, compared with n-butane,i-butane can produce strong signals of benzene at low temperature in its pyrolysis due to the enhanced formation of benzene precursors like propargyl and C4 species, which provides experimental clues to explain the higher sooting tendencies of iso-alkanes than n-alkanes. 展开更多
关键词 N-BUTANE /-Butane Flow reactor pyrolysis Synchrotron vacuum ultravioletphotoionization mass spectrometry Product identification Mass spectrometric analysis
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Simultaneous separation and determination of four main isoflavonoids in Astragali Radix by an isocratic LC/ESI-MS method 被引量:2
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作者 王玉林 梁逸曾 +3 位作者 张洁 冯晓亮 葛承胜 黄兰芳 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第2期303-309,共7页
A simple, reliable and rapid isocratic liquid chromatography(LC)-mass spectrometric detection(MS) coupled with electrospray ionization(ESI) method for simultaneous separation and determination of calycosin-7-O-β-D-gl... A simple, reliable and rapid isocratic liquid chromatography(LC)-mass spectrometric detection(MS) coupled with electrospray ionization(ESI) method for simultaneous separation and determination of calycosin-7-O-β-D-glucoside, ononin, calycosin and formonometin in Astragali Radix was developed. After the samples were extracted with ethanol, the optimum separation conditions for these analytes were achieved using water and acetonitrile(70:30, v/v) containing 0.2%(v/v) acetic acid as a mobile phase and a 2.0 mm×150 mm Hypersil-Keystone C18 column. Selective ion monitoring(SIM) mode and [M+H]+ ions at m/z 447, 431, 285 and 269 were used for quantitative analysis of four main active components above mentioned. The calibration curves were linear in the range of 0.4-175.0 μg/mL for calycosin-7-O-β-D-glucoside, 0.2-146.0 μg/m L for ononin, 0.4-210.0 μg/mL for calycosin and 0.5-217.0 μg/mL for formonetion, respectively. The limits of quantification(LOQ) and detection(LOD) were 0.4 μg/mL and 0.08 μg/m L for calycosin-7-O-β-D-glucoside, 0.2 μg/mL and 0.06 μg/m L for ononin, 0.4 μg/mL and 0.1 μg/mL for calycosin, 0.5 μg/m L and 0.1 μg/m L formonetion, respectively. The standard recoveries were in the range of 96.5%-104.7%. The developed method has successfully been used for the determination of four main flavonoids in Astragali Radix from various sources and can be used for identification, differentiation and quality evaluation of Astragali Radix. 展开更多
关键词 liquid chromatography electrospray ionization (ESI) mass spectrometric detection (MS) ISOFLAVONOIDS Astragali Radix
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Mineral Chemistry of Two-Mica Granite Rare Metals: Impact of Geophysics on the Distribution of Uranium Mineralization at El Sela Shear Zone, Egypt 被引量:3
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作者 Ibrahim Gaafar Michel Cuney Ahmed Abdel Gawad 《Open Journal of Geology》 2014年第4期137-160,共24页
The present work aims at identifying Nb-Ta-, Zr-Hf-, REE-, Th-U-bearing two-mica granite from geological, geophysical cross-sections and mineral chemistry studies from three boreholes at G. El Sela shear zone. Microsc... The present work aims at identifying Nb-Ta-, Zr-Hf-, REE-, Th-U-bearing two-mica granite from geological, geophysical cross-sections and mineral chemistry studies from three boreholes at G. El Sela shear zone. Microscopically, the three boreholes are composed mainly of two-mica granite. They are composed of K-feldspar, plagioclase, quartz, biotite and muscovite. Accessories are pyrite, zircon, fluorite, rutile, monazite with Th-U-mineralization identified by scanning electron microscope (SEM) and electron probe-microanalyses (EPMA). Chlorite, muscovite, sericite, kaolinite are secondary minerals. Geochemically, two-mica granite boreholes are A-type granites and peraluminous characteristics. They are enriched in large ion lithophile elements (LILE;Ba, Rb and Sr), high field strength elements (Y, Zr and Nb), and LREE but depleted in HREE with negative Eu anomaly. U-enrichment associated with chloritization, muscovitization, albitization, sericitization, kaolinization and argillization results from convective hydrothermal circulation of fluids through brittle structures along the ENE-WSW main shear zone. The ratios Nb/Ta (7.7 - 17.7) and Zr/Hf (16.9 - 26.4) are relatively enriched in the lighter isovalents Ta and Hf. The accessory minerals observed in the two-mica granites are represented by metallic sulfides (pyrite, arsenopyrite, chalcopyrite, galena and sphalerite), Nb-rutile, Hf-zircon, fluorite, monazite, columbite, betafite, thorite, phosphothorite, uranothorite, brannerite, uraninite, coffinite and pitchblende at G. El Sela shear zone. Uraninite with a low Th content indicates a hydrothermal origin of U-mineralization, Thorite, uranothorite, monazite and zircon is the main uranium bearing minerals of magmatic origin within the enclosing granite. The primary U-mineralization has been observed in two boreholes. In order to illustrate the geophysical signature of El Sela U-mineralization, the radiometric, magnetic, and VLF-EM data as well as radon concentration are included. The magnetic, electrical conductivity and radiometric profiles were produced from detailed ground surveys. The shear zone is characterized by relatively weak levels for both K and eTh, but very high eU anomalies (<3500 ppm), Therefore, the Sela shear zone acts as a good trap for U-mineralization. The Sela Shear zone coincides with positive conductivity anomalies, which are the most prominent features on the respective profiles. The magnetic field over the Sela shear zone is also conspicuous by the sharp contrast which makes with the strong negative signatures of the altered microgranite. The radon distribution map showed the presence of seven high anomalies that are mostly controlled by the structures due to the easy movement of radon through them. 展开更多
关键词 BOREHOLES SHEAR Zone RADON Spectrometric Magnetic CONDUCTIVITY
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Application of non-equal interval GM(1,1)model in oil monitoring of internal combustion engine 被引量:2
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作者 陈士玮 李柱国 周守西 《Journal of Central South University of Technology》 EI 2005年第6期705-708,共4页
The basic difference non-equal interval model GM(1,1) in grey theory was used to fit and forecast data series with non-equal lengths and different inertias, acquired from oil monitoring of internal combustion engines.... The basic difference non-equal interval model GM(1,1) in grey theory was used to fit and forecast data series with non-equal lengths and different inertias, acquired from oil monitoring of internal combustion engines. The fitted and forecasted results show that the length or inertia of a sequence affects its precision very much, i.e. the bigger the inertia of a sequence is, or the shorter the length of a series is, the less the errors of fitted and forecasted results are. Based on the research results, it is suggested that short series should be applied to be fitted and forecasted; for longer series, the newer datum should be applied instead of the older datum to be analyzed by non- equalinterval GM(1,1) to improve the forecasted and fitted precision, and that data sequence should be verified to satisfy the conditions of grey forecasting. 展开更多
关键词 GM(1 1) model oil monitoring spectrometric analysis internal combustion engine
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Geophysical Mapping, Geochemical Evidence and Mineralogy for Nuweibi Rare Metal Albite Granite, Eastern Desert, Egypt 被引量:3
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作者 Ibrahim Gaafar 《Open Journal of Geology》 2014年第4期108-136,共29页
The present study aims to shed light on the rare metals of Nuweibiareaalbite granite in the Eastern Desert through the chemical analyses of the two types of fine-grained albite granite (FAG) and medium-grained albite ... The present study aims to shed light on the rare metals of Nuweibiareaalbite granite in the Eastern Desert through the chemical analyses of the two types of fine-grained albite granite (FAG) and medium-grained albite granite (MAG) in addition to mineralogical studies as well as ground spectrometric survey and aeromagnetic mapping. On the basis of ground spectrometric measurements K, eUand eTh distribution maps were obtained. The concentration of K, U and Th content shows maxima (4.5%, 13 ppm and 27 ppm on average, respectively) in the FAG, and (4.5%, 10 ppm and 35 ppm on average) in the MAG. The eU/eTh ratio significantly increases in FAG with higher magma differentiation than MAG reaching 0.63. This paper uses magnetic geophysical methods to investigate geometry and sense of motion across the Nuweibi area. The interpreted structures from the magnetic maps are characterized by two main intersecting sets of NW-SE and NE-SW trending faults in addition to other three minor faults that trend in N-S, NNW-SSE and ENE-WSW directions. The NW-SE trending faults represent the recent sets in the study area where they are dissected and displaced by the other old faults. The Werner depth map shows the interface depths of the granite and basement rocks that extend to great depths ranging from 10 to 380 m. FAG is extended underneath most of the surrounding schist rocks because of their attributed low magnetic intensity that confirmed also with drilling. Microscope and Microprobe analyses indicated that the most important radioactive minerals include uranothorite, thorite, zircon, and monazite. Columbite group minerals represent the most common Nb-Ta host in Nuweibi-albite granites that contain significant levels of Ta (up to 65.4 wt. % Ta2O5) and Nb (up to 60 wt. % Nb2O5), with Ta/(Ta+Nb) ratio ranging from 0.17 to 0.84. Columbite group minerals are represented mostly by columbite-(Mn) and tantalite-(Mn), with Mn/(Mn+Fe) ratio ranging from 0.42 to 0.89. Ixiolite, wodgnite and tapiolite-(Mn) were found only in the FAG indicating the final stages of the evolution of parental granitic magma. The U-Th and U-K variation diagrams suggested that magmatic processes controlled the distribution of these elements. The Scanning Electron-microprobe analyses reveal variable compositions and extents between the MAG and FAG in the Nb, Ta-Ti, Sn-Fe, Mn triangular plot. It is worthy to be noted that because of the higher Ta/Nb ratio in the tapiolite-Mn and ixiolite of FAG in comparison with the coexisting Mn-columbite in the MAG, levels of HfO2 greater than 15% and even attaining 23%, characterized the hafnium zircon in the Nwueibialbite-enriched facies. There is a close correlation between Hf/(Hf + Zr) and Ta/(Nb + Ta) which seems mainly associated with the FAG. 展开更多
关键词 ALBITE Spectrometric Magnetic Columbo-Tantalite Ixiolite Thorite
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Spectrometric study of α-methylene aromatic araminenone and aminoketone 被引量:1
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作者 Li Yuan Mou Zi Yun Lin +1 位作者 Li Ya Zhu Xiao Tian Liang 《Chinese Chemical Letters》 SCIE CAS CSCD 2007年第10期1253-1255,共3页
Thirteen α-methylene aromatic araminenone and four α-methylene aromatic aminoketones were prepared by modified Mannich reaction. On the basis of isotopic labeling, a plausible way of cleavage was proposed for the fo... Thirteen α-methylene aromatic araminenone and four α-methylene aromatic aminoketones were prepared by modified Mannich reaction. On the basis of isotopic labeling, a plausible way of cleavage was proposed for the formation of the M^+- 17 fragment peak in the MS of the α-methylene aromatic araminenone and aminoketones. The characteristic chemical shift of the olefinic protons in ^1H NMR is also discussed. 展开更多
关键词 α-Methylene aromatic araminenone and aminoketones Spectrometric study
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Detection of Optical Stability of chiral 2-Methylbutyric Acid in Gas Phase with Quadrupole-Quistor-Quadrupole Mass Spectrometer
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作者 Yuan Jiang PANI U.P.SCHLUNEGGERZ(Department of Chemistry, Zhejiang University, Hangzhou 310027)(Department of Chemistry and Biochemistry. Berne University, CH-30 12 Bern,Switzerland) 《Chinese Chemical Letters》 SCIE CAS CSCD 1999年第3期213-214,共2页
Optical stability of chiral 2-methylbutyric acid in gas phase has been detected with Quadrupole-Quistor-Quadrupole tandem mass spectrometer in combination with deuteration. The results show that these compounds are op... Optical stability of chiral 2-methylbutyric acid in gas phase has been detected with Quadrupole-Quistor-Quadrupole tandem mass spectrometer in combination with deuteration. The results show that these compounds are optically unstable in the process of self chemical ionization. 展开更多
关键词 2-methylbutyric acid optical stability mass spectrometric detection
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A Novel Approach for Determining the Orientation of 3-Hydroxyl Group of Some Steroids by CIMS
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作者 Yuan Jiang PAN Yao Zu CHEN(Department of Chemistry, Zhejiang University, Hangzhou 310027) 《Chinese Chemical Letters》 SCIE CAS CSCD 1999年第2期143-144,共2页
Trimethylchlorosilane was used as a stereoselective reagent to determine the e or a orientation of 3-hydroxyl group of some steroids by chemical ionization mass spectrometry.
关键词 orientation of 3-hydroxyl group STEROIDS mass spectrometric determination
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GAS CHROMATOGRAPHIC-MASS SPECTROMETRIC ANALYSIS OF ANABOLIC STEROIDS IN HUMAN URINE
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作者 Ji ZHANG Chun Sheng LIU Tong Hui ZHOU (Institute of Materia Medica,1 Xian Nong Tan Street,Beijing 100050,P.R.China)Yi Zhong ZHANG Chang Jiu ZHANG Li YE (+ National Research Institute of Sports Medicine,11 Tiyuguan Road,Beijing 100061) 《Chinese Chemical Letters》 SCIE CAS CSCD 1990年第2期143-146,共4页
A new GC/MS method for detection and identification of 19 anabolic steroids in human urine is presented.The procedure involves adsorption and isolation on a macroporous XAD-2 resin,enzymatic hydrolysis,alkaline extrac... A new GC/MS method for detection and identification of 19 anabolic steroids in human urine is presented.The procedure involves adsorption and isolation on a macroporous XAD-2 resin,enzymatic hydrolysis,alkaline extraction,derivatization,GC separation and MS detec- tion.Gas chromatographic-mass spectrometric data illustrate artifacts arising from enzymatic hydrolysis of steroid glucuronides and the structural characterization of their metabolites. Using this method,metabolic studies of these steroids in human urine were made after their ingestion by normal and healthy male volunteers.This method was proven to be suitable for large-scale routine analysis of anabolic steroids and was used successfully in passing the doping control test held by the Medical Commission of the International Olympic Committee. 展开更多
关键词 GAS CHROMATOGRAPHIC-MASS SPECTROMETRIC ANALYSIS OF ANABOLIC STEROIDS IN HUMAN URINE der GC
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Spectrometric Study of α-Phenylcinnamic Acids
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作者 Xin HE Li Yuan MOU +2 位作者 Zi Yun LIN Li Ya ZHU Xiao Tian LIANG (Institute of Materia Medica , Chinese Academy of Medical Sciences and Peking Union Medical College . Beijing 100050 ) 《Chinese Chemical Letters》 SCIE CAS CSCD 1997年第10期883-884,共2页
Fourteen substituted α-phenylcinnamic acids were prepared by the classical Perkin condensation. A plausible way of cleavage was involved in the formation of the specific fragment peaks in the MS of the α-phenylcinn... Fourteen substituted α-phenylcinnamic acids were prepared by the classical Perkin condensation. A plausible way of cleavage was involved in the formation of the specific fragment peaks in the MS of the α-phenylcinnamic acids . The characteristic chemical shift of the olefinic proton in HNMR is also discussed 展开更多
关键词 Spectrometric Study of Phenylcinnamic Acids
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TWO NEW COMPOUNDS FROM THE MUSHROOM D. INDUSIATA (VENT EX PERS) FISCH
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作者 Giovanni Vidari Paola Vita-Finzi 《福建分析测试》 CAS 1997年第4期740-746,共7页
The chemical constituents in ethyl acetate extract from the mushroom D. Indusiata Fisch were studied. Two new compounds (a new terpenol oleate and a new sesquiterpene) were isolated and identitied by using IR, NMR and... The chemical constituents in ethyl acetate extract from the mushroom D. Indusiata Fisch were studied. Two new compounds (a new terpenol oleate and a new sesquiterpene) were isolated and identitied by using IR, NMR and MS techniques. 展开更多
关键词 ISOLATION spectrometric analyses terpenol OLEATE sesuiterpene DICTYOPHORA indusiata
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Spatial distribution of SiCln (n=O-2) in SICl4 plasma measured by mass spectroscopy
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作者 王照奎 林揆训 +2 位作者 娄艳辉 林璇英 祝祖送 《Chinese Physics B》 SCIE EI CAS CSCD 2006年第10期2374-2377,共4页
For a better understanding of the deposition mechanism of thin films in SiCl4 source gas, we have measured the spatial distributions of SiCln (n=0-2) radicals in SICl4 radio frequency glow discharge plasma utilizing... For a better understanding of the deposition mechanism of thin films in SiCl4 source gas, we have measured the spatial distributions of SiCln (n=0-2) radicals in SICl4 radio frequency glow discharge plasma utilizing a mass spectrometer equipped with a movable gas sampling apparatus. The experimental results demonstrate that the relative densities of SiCln (n=0-2) radicals have peak values at the position of 10 mm above the powered electrode along the axial direction; the relative densities of the Si and SiCIn (n=1, 2) radicals have peak values at the positions of 27mm and 7 mm away from the axis along the radial direction, respectively. Generally speaking, in the whole SICl4 plasma bulk region, the relative density of Si is one order of magnitude higher than that of SICl, and the relative density of SiCl is several times higher than that of SICl2. This reveals that Si and SiCl may be the primary growth precursors in forming thin films. 展开更多
关键词 SiCln (n=0-2) neutral radicals spatial distribution mass spectrometric diagnosis
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Synthesis of a Novel Imidazole Ionic Liquid Modified Mesoporous Silica SBA15 for Selective Separation and Determination of Inorganic Arsenic in Rice
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作者 CHEN Tuan-Wei ZHEN Wen-Bo +3 位作者 YAN Zhi-Ming LIN He-Tong CHEN Guo-Ying CHEN Shao-Jun 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2018年第12期2024-2035,1848,共13页
A novel 1-methylimidazole ionic liquid modified SBA15 mesoporous silica(1-MIIL@SBA15) was synthesized and applied to selective separation of inorganic arsenic(iAs) in rice by dispersive solid phase extraction(DSPE), f... A novel 1-methylimidazole ionic liquid modified SBA15 mesoporous silica(1-MIIL@SBA15) was synthesized and applied to selective separation of inorganic arsenic(iAs) in rice by dispersive solid phase extraction(DSPE), followed by hydride generation-atomic fluorescence spectrometric(HG-AFS) quantification. The prepared sorbent was characterized by FTIR, FESEM, BET and Zeta potential. Key parameters of adsorption and desorption in DSPE were optimized using standard reference material 1568 b rice flour. Under optimal conditions, the limit of detection was 8.776 ng/kg, relative standard deviation was ≤2.0%, and recoveries of iAs were in the 92.3~94.4% range. This method was successfully applied to the determination of iAs in rice. Under acidic condition, the electrostatic interaction between the positively charged 1-MIIL@SBA15 and anionic iAs played an important role in selective iAs separation, rendering this method suitable for iAs analysis. 展开更多
关键词 SBA15 ionic liquid inorganic arsenic dispersive solid phase extraction hydride generation-atomic fluorescence spectrometric(HG-AFS)
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Mass Spectrometric Study of Clusters Produced by Laser Vaporization of Some Phosphates
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作者 Xiang Hong LIU Xiao Guang ZHANG +2 位作者 Yue LI Xiu Yan WANG and Nan Quan LOU(State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023) 《Chinese Chemical Letters》 SCIE CAS CSCD 1997年第9期805-806,共2页
The clusters generated by direct laser vaporization of KH2PO4 and Cu-3(PO4)(2) samples are studied by a TOF mass spectrometer. It is found that mainly the [K(KPO3)(n)]* cluster series is generated from KH2PO4 sample a... The clusters generated by direct laser vaporization of KH2PO4 and Cu-3(PO4)(2) samples are studied by a TOF mass spectrometer. It is found that mainly the [K(KPO3)(n)]* cluster series is generated from KH2PO4 sample and it demonstrates obvious magic numbers, which are n=3, 6, 9, 12, 15. Direct laser vaporization of Cu-3(PO4)(2) sample produced [Cu(CuPO3)n]* cluster series as well as other series with the same building block of (CUPO3). 展开更多
关键词 Mass Spectrometric Study of Clusters Produced by Laser Vaporization of Some Phosphates KPO
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Determination of Fenofibrate and the Degradation Product Using Simultaneous UV-Derivative Spectrometric Method and HPLC
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作者 Fathy M. M. Salamaa Mohamed W. I. Nassar +2 位作者 Mohie M. K. Sharaf El-Din Khalid A. M. Attia Mohamed Yousri Kaddah 《American Journal of Analytical Chemistry》 2011年第3期332-343,共12页
Two new selective, precise, and accurate methods were developed for the determination of fenofibrate in the presence of its basic degradation product. In the first method fenofibrate was determined using an algorithm ... Two new selective, precise, and accurate methods were developed for the determination of fenofibrate in the presence of its basic degradation product. In the first method fenofibrate was determined using an algorithm bivariate calibration derivative method, in which an optimum pair of wavelengths was chosen for the determination of different binary mixtures. In the second method (HPLC), separation was achieved on RESTEK Pinnacle II phenyl column (5 μm, 250 × 4.6 mm) and Pinnacle II phenyl (5 μm, 10 × 4 mm) guard cartridge using a mobile phase consisting of methanol –0.1% phosphoric acid (60:40, v/v) at a flow rate 2 mL●min–1, and the column oven temperature was set at 50°C. The UV detector was time programmed at 302 nm and 289 nm for the internal standard (I.S.) and fenofibrate, respectively. The proposed methods were successfully applied for the determination of fenofibrate and its degradation product in the laboratory-prepared mixture and in pharmaceutical formulation. The assay results obtained using the bivariate method were statistically compared to those of the HPLC method and good agreement was observed. 展开更多
关键词 FENOFIBRATE Stability Degradation Product UV DERIVATIVE Spectrometric METHOD HPLC
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Subsoil Natural Physico-Chemical Reactor:Regularity of Natural Processes of Synthesis of Perfect Diamond Crystals
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作者 J.M.Svoren 《Journal of Geological Resource and Engineering》 2020年第4期133-136,共4页
Studies of inclusions(defects)in minerals have shown that the source of carbon in the natural processes of synthesis of perfect diamond crystals is mantle carbon dioxide,(СО2)Р=6.1МPаandδ13С=(-6.1±0.5)‰.A... Studies of inclusions(defects)in minerals have shown that the source of carbon in the natural processes of synthesis of perfect diamond crystals is mantle carbon dioxide,(СО2)Р=6.1МPаandδ13С=(-6.1±0.5)‰.A new mechanism for the synthesis of natural crystals of diamond,pyrope,magnetite,quartz,etc.has been developed.It is shown that under the influence of a powerful pulse of tectonogenic energy in some parts of the lithosphere that there are deep faults-tubes,which take root-migrating melt in the direction of the earth’s crust.During migration in the contact zone—“melt-lithosphere rocks”due to their contact interaction-friction,a high-voltage electric field of complex shape is formed,in which CO2 turns into an energy-excited state,its molecules decompose into individual radicals and atoms.In the melt-electrolyte under the influence of an electric field,ions-cations move in certain directions depending on the configuration of the field,which is due to magma,contact with rocks of the lithosphere and the speed of magma in the gap-tube.As they move,these ions undergo numerous collisions with the molecules present there,in particular,СО2 and its atoms and radicals,temporarily forming unstable compounds that fall into the zone with existing iron compounds,etc.OxygenСО2 poatomically detaches from the molecule and forms FeO·Fe2O3(magnetite),and the most energetically advantageous for chemically active carbon atoms in such an environment is that the melt bonds together form a diamond crystal.The isolated SiO2 molecules chemically form a group of garnets,quartz,and the like. 展开更多
关键词 Mass spectrometric method of research MELT fluid inclusions asthenospheric carbon dioxide
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Chemical Analysis of Magnesia and Magnesia-Alumina Refractory Materials——Flame atomic absorption spectrometric method for determination of calcium oxide content
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作者 ZHANG Xiaohui 《China's Refractories》 CAS 2006年第4期41-43,共3页
1 Scope This standard specifics the determination of calcium oxide coutent by flame atomic absorption spectrometric method.
关键词 Chemical Analysis of Magnesia and Magnesia-Alumina Refractory Materials Flame atomic absorption spectrometric method for determination of calcium oxide content
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