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含有机硅三元多嵌段共聚物的研究5.含有机硅三元多嵌段共聚物的形态结构 总被引:1,自引:1,他引:0
利用DMA,TEM和SAXS对PSF-PDMS-PHSn,PSF-PDMS-PHEn,PPO-PDMS-PHSn和PHS-PDMS-PBEn四种三元多嵌段共聚物的形态结构进行了研究,结果表明,不同三元多嵌段共聚物中三种链段的相互作用情况不同,其动态力学性能和形态结构有很大差异,并与嵌段共聚物微相分离的几种基本形态不同,特别是通过TEM在PSF-PDMS-PHSn和PPO-PDMS-PHSn中观察到清晰的互容界面相。 相似文献
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超大孔Fe和V—Ti分子筛的合成 总被引:1,自引:0,他引:1
水热法合成了具有超大孔MCM-41分子筛结构的含Fe和V-Ti分子筛,通过XRD,骨架IR,ESR,^29SiMAS NMR,紫外漫反射等测试表征证实,Fe原子在FeMCM-41分子筛骨架上,V和Ti同是进入V-TiMCM-41分子筛骨架。 相似文献
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水热法合成了具有超大孔MCM-41分子筛结构的含Pe和V-Ti分子筛,通过XRD、骨架IR、ESR、 ̄(29)SiMASNMR、紫外漫反射等测试表征证实,Fe原子在FeMCM-41分子筛骨架上,V和Ti同时进入V-TiMCM-41分子筛骨架。FeMCM-41的骨架红外谱除Fe分子筛的特征吸收峰660cm ̄(-1)外,还显示960cm ̄(-1)峰,ESR谱出现高对称八面体环境Fe(Ⅲ)信号(g=2.0)和扭曲四面体环境Fe(Ⅲ)信号(g=4.2),而V-TiMCM-41的骨架红外960cm ̄(-1)峰强度分别随分子筛中钛或钒的含量线性增强。约在g=1.98处出现的超精细结构ESR信号表明V以分散的不流动的V ̄(4+)形式存在,化学分析结果表明骨架上Ti和V原子相互间不排斥。 相似文献
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本文分析介绍了三个最广泛使用的聚合物液体状态方程,Flory、SL和SS方程及作者开发的三个新方程SHT、SHTF和OCM的理论基础和假设,并用15个聚合物液体、17个大分子量烃液体和6个常用有机溶剂的P-V-T数据作了比较。结果表明,OCM方程精度最好,其他方程精度按SS、SHT、SHTF、Flory、SL依次变差。结论是开放胞腔更接近液体的真实结构,空穴的引入可以改进胞腔理论的计算精度,L-J位能可以较好地反映液体中分子间的作用力。 相似文献
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本文分析了乙二胺和正丁胺为模板剂,在水热体系Na2O-SiO2-Al2O3-H2O中合成了ZSM-35沸石,并利用XRD,SEM,IR及CO加氢反应手段考察了其物理化学特性。结果表明,模板剂对ZSM-35沸石的合成,结构,形貌,红外振动,稳定性及催化性能有显著的影响作用。 相似文献
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用XRD、FTIR、TG-DTA、^13C魔角固体核磁共振表征用四甲基乙基二胺(TMEDA)为结构异向剂合成的高硅沸石CF-3及ZSM-39.TMEDA不同基团的^13C化学位移,共振峰相对强度在交叉极化(CP)及高功率去偶(HPDEC)核磁共振谱中的变化,揭示出模板分子在尺寸不同的沸石笼中的位置、运动状态及其与骨架的相互作用。在ZSM-39沸石中的TMEDA分子,它的-C2H4-基团^13C共振 相似文献
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González-Rodríguez MJ Garrido-Frenich A Arrebola FJ Martínez-Vidal JL 《Rapid communications in mass spectrometry : RCM》2002,16(12):1216-1224
A rapid multiresidue method for the analysis of 72 pesticides has been developed using a single injection with low-pressure gas chromatography/tandem mass spectrometry (LP-GC/MS/MS). The LP-GC/MS/MS method used a short capillary column of 10 m x 0.53 mm i.d. x 0.25 microm film thickness coupled with a 0.6 m x 0.10 mm i.d. restriction at the inlet end. Optimal LP-GC conditions were determined which achieved the fastest separation in MS/MS detection mode. Also MS/MS conditions were optimized in order to increase sensitivity and selectivity. The analytical parameters of the LP-GC/MS/MS method were compared with those obtained by GC/MS/MS using a conventional capillary column (30 m x 0.25 mm i.d. x 0.25 microm film thickness). Better precision and sensitivity values were obtained with the LP-GC/MS/MS approach. The limits of detection (LOD) of the compounds ranged from 0.1 to 14.1 microg L(-1) for LP-GC/MS/MS, lower than those obtained for conventional GC/MS/MS that ranged from 0.1 to 17.5 microg L(-1). The peak widths obtained with the short column in LP-GC are similar to those obtained using conventional capillary GC columns, and the peaks can be successfully identified by MS/MS detection with the conventional scan speed of ion-trap instruments. In addition, the analysis time was significantly reduced with LP-GC/MS/MS (32 min) versus GC/MS/MS (72 min), allowing the number of samples analyzed per day in a routine laboratory to be doubled. 相似文献
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Bodnar WM Blackburn RK Krise JM Moseley MA 《Journal of the American Society for Mass Spectrometry》2003,14(9):971-979
The goal of this work was to evaluate the improvement in proteome coverage of complex protein mixtures gained by analyzing samples using both LC/ESI/MS/MS and LC/MALDI/MS/MS. Parallel analyses of a single sample were accomplished by interfacing a Probot fractionation system with a nanoscale LC system. The Probot was configured to perform a post-column split such that a fraction (20%) of the column effluent was sent for on-line LC/ESI/MS/MS data acquisition, and the majority of the sample (80%) was mixed with a matrix solution and deposited onto the MALDI target plate. The split-flow approach takes advantage of the concentration sensitive nature of ESI and provides sufficient quantity of sample for MALDI/MS/MS. Hybrid quadrupole time-of-flight mass spectrometers were used to acquire LC/ESI/MS/MS data and LC/MALDI/MS/MS data from a tryptic digest of a preparation of mammalian mitochondrial ribosomes. The mass spectrometers were configured to operate in a data dependent acquisition mode in which precursor ions observed in MS survey scans are automatically selected for interrogation by MS/MS. This type of acquisition scheme maximizes the number of peptide fragmentation spectra obtained and is commonly referred to as shotgun analysis. While a significant degree of overlap (63%) was observed between the proteins identified in the LC/ESI/MS/MS and LC/MALDI/MS/MS data sets, both unique peptides and unique proteins were observed by each method. These results demonstrate that improved proteome coverage can be obtained using a combination of these ionization techniques. 相似文献
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Lee JS Kim DH Liu KH Oh TK Lee CH 《Rapid communications in mass spectrometry : RCM》2005,19(23):3539-3548
Searchable MS/MS spectra libraries, constructed using the results of liquid chromatography coupled with electrospray ionization (ESI) tandem mass spectrometry (LC/MS/MS) with data-dependent acquisition on an ion trap mass spectrometer, are presented with regard to the identification and confirmation of a variety of closely related flavonoids in a set of biological samples. Flavonoids were found to exhibit a maximum amount of structurally specific MS/MS spectra at 45% of normalized collision energy on the instrument used, without wideband activation. These MS/MS spectra were then searched automatically against a 297-substance MS/MS library that contains many previously acquired spectra of standard flavonoids. The possible applications of this powerful technique to biological samples are also discussed. Daidzein and genistein were identified through the MS/MS spectra library while searching through LC/MS/MS data for plant and microbial extracts. Moreover, these compounds proved completely distinguishable from other flavonoids of closely related structures in the MS/MS spectra library, using the NIST MS search program. The applicability of the library-searchable spectra at low concentrations was demonstrated by successful identification of daidzein and genistein at 0.05 and 0.5 microg/mL, respectively. 相似文献
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A quantitative Ultra Performance liquid chromatography/tandem mass spectrometry (UPL/MS/MS) protocol was developed for a five-compound mixture in rat plasma. A similar high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) quantification protocol was developed for comparison purposes. Among the five test compounds, three preferred positive electrospray ionization (ESI) and two preferred negative ESI. As a result, both UPLC/MS/MS and HPLC/MS/MS analyses were performed by having the mass spectrometer collecting ESI multiple reaction monitoring (MRM) data in both positive and negative ion modes during a single injection. Peak widths for most standards were 4.8 s for the HPLC analysis and 2.4 s for the UPLC analysis. There were 17 to 20 data points obtained for each of the LC peaks. Compared with the HPLC/MS/MS method, the UPLC/MS/MS method offered 3-fold decrease in retention time, up to 10-fold increase in detected peak height, with 2-fold decrease in peak width. Limits of quantification (LOQs) for both HPLC and UPLC methods were evaluated. For UPLC/MS/MS analysis, a linear range up to four orders of magnitude was obtained with r2 values ranging from 0.991 to 0.998. The LOQs for the five analytes ranged from 0.08 to 9.85 ng/mL. Three levels of quality control (QC) samples were analyzed. For the UPLC/MS/MS protocol, the percent relative standard deviation (RSD%) for low QC (2 ng/mL) ranged from 3.42 to 8.67% (N = 18). The carryover of the UPLC/MS/MS protocol was negligible and the robustness of the UPLC/MS/MS system was evaluated with up to 963 QC injections. 相似文献
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Piotr Zabielski G. Charles Ford X. Mai Persson Abdul Jaleel Jerry D. Dewey K. Sreekumaran Nair 《Journal of mass spectrometry : JMS》2013,48(2):269-275
Precise measurement of low enrichment of stable isotope labeled amino‐acid tracers in tissue samples is a prerequisite in measuring tissue protein synthesis rates. The challenge of this analysis is augmented when small sample size is a critical factor. Muscle samples from human participants following an 8 h intravenous infusion of L‐[ring‐13C6]phenylalanine and a bolus dose of L‐[ring‐13C6]phenylalanine in a mouse were utilized. Liquid chromatography tandem mass spectrometry (LC/MS/MS), gas chromatography (GC) MS/MS and GC/MS were compared to the GC‐combustion‐isotope ratio MS (GC/C/IRMS), to measure mixed muscle protein enrichment of [ring‐13C6]phenylalanine enrichment. The sample isotope enrichment ranged from 0.0091 to 0.1312 molar percent excess. As compared with GC/C/IRMS, LC/MS/MS, GC/MS/MS and GC/MS showed coefficients of determination of R2 = 0.9962 and R2 = 0.9942, and 0.9217 respectively. However, the precision of measurements (coefficients of variation) for intra‐assay are 13.0%, 1.7%, 6.3% and 13.5% and for inter‐assay are 9.2%, 3.2%, 10.2% and 25% for GC/C/IRMS, LC/MS/MS, GC/MS/MS and GC/MS, respectively. The muscle sample sizes required to obtain these results were 8 µg, 0.8 µg, 3 µg and 3 µg for GC/C/IRMS, LC/MS/MS, GC/MS/MS and GC/MS, respectively. We conclude that LC/MS/MS is optimally suited for precise measurements of L‐[ring‐13C6]phenylalanine tracer enrichment in low abundance and in small quantity samples. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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High-throughput GC/MS and HPLC/MS/MS techniques for the multiclass, multiresidue determination of 653 pesticides and chemical pollutants in tea 总被引:1,自引:0,他引:1
Pang GF Fan CL Zhang F Li Y Chang QY Cao YZ Liu YM Li ZY Wang QJ Hu XY Liang P 《Journal of AOAC International》2011,94(4):1253-1296
An efficient and sensitive method has been established for simultaneous determination of 653 pesticides in teas by GC/MS and HPLC/MS/MS. The method involved extraction with acetonitrile followed by cleanup using Cleanert-TPT SPE and subsequent identification and quantitation of 490 pesticides by GC/MS and 448 pesticides by HPLC/MS/ MS. The LODs for pesticides determined by GC/MS were between 1.0 and 500 microg/kg, and those determined by HPLC/MS/MS were between 0.03 and 4820 microg/kg. At the low fortification levels of 0.01-100 microg/kg, the average recoveries of 94% of the pesticides determined by GC/MS were between 60 and 120%, 77% of which had an RSD below 20%. For 91% of pesticides determined by HPLC/MS/MS, the average recoveries were between 60 and 120%, 76% of which had an RSD below 20%. The paper also reports a novel SPE column, Cleanert TPT, which comprised graphitized carbon black (PestiCarb), polyamine silica, and amide polystyrene for purifying the tea samples. The results indicated good repeatiblity and reproducibility. 相似文献
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Jiang H Somogyi A Timmermann BN Gang DR 《Rapid communications in mass spectrometry : RCM》2006,20(20):3089-3100
The gingerols, including [6]-, [8]-, and [10]-gingerols, a series of chemical homologs differentiated by the length of their unbranched alkyl chains, have been identified as major active components in fresh ginger rhizome. The purpose of this study was to investigate the utility of ion trap liquid chromatography/tandem mass spectrometry (LC/MS/MS) as an online tool to identify and quantify these compounds in raw or processed ginger rhizome samples. Negative mode electrospray ionization (ESI) was used in MS, MS/MS and MS(n) experiments in quadrupole ion trap instruments from two different manufacturers and in high-resolution and accurate mass MS and MS/MS experiments in a Fourier transform ion cyclotron resonance mass spectrometer to elucidate the ionization and fragmentation mechanisms of these compounds in these instruments. Positive mode ESI, which generated many more fragment ions in full scan MS even under gentle ionization conditions, was also used in LC/MS and MS/MS experiments and in direct infusion MS and MS/MS experiments. Consistent and predictable ionization and fragmentation behaviors were observed for all gingerols when analyzed in the same instrument. Instruments from different manufacturers, however, had different ionization mechanisms. The major difference between instruments was their ability to form covalent dimer adducts of the gingerols. Subsequent fragmentation patterns of the precursor ions were essentially identical. These results clearly demonstrate that LC/MS instruments produce data that cannot necessarily be replicated in other laboratories, especially if those laboratories do not have the same instrument model from the same manufacturer. This presents major problems for metabolite target analysis, metabolic profiling and metabolomics investigations, which would benefit from LC/MS mass spectrum libraries as they do from GC/MS mass spectrum libraries, because such libraries may not be valid across platforms. 相似文献
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Pesticide residues in fruit and vegetables were determined by gas chromatography/tandem mass spectrometry (GC/MS/MS). Electron impact (EI)/MS/MS and chemical ionization (CI)/MS/MS were developed for 80 compounds, including organochlorine, organophosphorus, organonitrogen, and pyrethroids, providing unambiguous spectral confirmation for these complex matrixes. Residues were extracted from samples with acetone followed by a mixture of dichloromethane-petroleum ether. Two injections per sample were required for analysis of the entire pesticide list by EI/MS/MS and CI/MS/MS. Initial steps involving cleanup and concentration of extracts were eliminated. The excellent selectivity and good linearity allowed quantification and identification of low levels of pesticides in the most difficult matrixes. The method has been used for routine analysis of many vegetables. 相似文献
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The determination of tetra- to octachlorodibenzo-p-dioxins and tetra- to octachlorodibenzofurans (PCCD/Fs) by high-resolution gas chromatography/tandem mass spectrometry (HRGC/MS/MS) and high-resolution gas chromatography/triple mass spectrometry (HRGC/MS(3)) in a quadrupole ion trap, equipped with an external ion source, is presented. MS/MS involves a typical four-step process, namely ionization, parent ion isolation, collision-induced dissociation (CID) and mass analysis of the daughter ions. For the MS(3) experiment, the MS/MS scan function is used with the addition of selected daughter ion isolation, their CID and the mass analysis of second-generation product ions called 'grand-daughter ions.' For both methods, the energies necessary for the CID of the 17 PCDD/Fs were determined and optimized using multiple scan functions with different CID amplitudes. The CID efficiency, defined as the signal ratio of fragment ions detected from the major dissociation channels to molecular ions isolated, was 1.15-2.40 V for parent ion dissociation (MS/MS) and 1.05-1.50 V for daughter ion dissociation (MS(3)) and for all the chloro congeners. The same sensitivity (1 pg microl(-1)) can be reached with both the MS/MS and MS(3) methods and linear responses were obtained between 1 and 100 pg microl(-1) injected. 相似文献