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991.
Limei Sun Kristine Spildo Ketil Djurhuus Arne Skauge 《Journal of Dispersion Science and Technology》2014,35(4):551-555
A laboratory selection of salinity for a low salinity water-low salinity surfactant (LS-LSS) process is presented in this paper with systematical investigation on surfactant phase behavior, interfacial tension (IFT), and dynamic retention in porous media with IOS2024 and isoamyl alcohol (IAA) as surfactant system. The results show that 0.4 wt% IOS2024 with 1 wt% IAA can provide ultra-low IFT of 10?3 mN/m at around 3000–4000 mg/L total dissolved solids, but at that salinity range the surfactant retention is very high. The search for an optimum surfactant formulation has to consider solution properties and retention in addition to the low IFT. The salinity for a LS-LSS process should thus not be focused on either optimal salinity or ultra-low IFT, but instead the best choice could be a compromise between the properties in question. The three-phase region, where ultra-low IFT are found, is also associated with high retention values. However, we show that as salinity is increased from a two-phase region with oil solubilized in a water continuous microemulsion, there is a region close to the three-phase boundary which has potential. This region does not give ultra-low, but fairly low (10?2 mN/m in this case) interfacial tensions, and also significantly lower retention. 相似文献
992.
Wen Zhou Xiao-Li Sun Lin Gu Fei-Fei Bao Xin-Xin Xu Chun-Yan Pang Zhi-Guo Gu Zaijun Li 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(2):843-852
Three new mesoporous silica materials IL15SGs (HF15SG, TF15SG and DF15SG) doped with benzo-15-crown-5 and imidazolium based ionic liquids (C8mim+PF6 ?, C8mim+BF4 ? or C8mim+NTf 2 ? ) have been prepared by a simple approach to separating lithium isotopes. The formed mesoporous structures of silica gels have been confirmed by transmission electron microscopy image and N2 gas adsorption–desorption isotherm. Imidazolium ionic liquids acted as templates to prepare mesoporous materials, additives to stabilize extractant within silica gel, and synergetic agents to separate the lithium isotopes. Factors such as lithium salt concentration, initial pH, counter anion of lithium salt, extraction time, and temperature on the lithium isotopes separation were examined. Under optimized conditions, the extraction efficiency of HF15SG, TF15SG and DF15SG were found to be 11.43, 10.59 and 13.07 %, respectively. The heavier isotope 7Li was concentrated in the solution phase while the lighter isotope 6Li was enriched in the gel phase. The solid–liquid extraction maximum single-stage isotopes separation factor of 6Li–7Li in the solid–liquid extraction was up to 1.046 ± 0.002. X-ray crystal structure analysis indicated that the lithium salt was extracted into the solid phase with crown ether forming [(Li0.5)2(B15)2(H2O)]+ complexes. IL15SGs were also easily regenerated by stripping with 20 mmol L?1 HCl and reused in the consecutive removal of lithium ion in five cycles. 相似文献
993.
Characterization of radioactive cobalt on graphene oxide by macroscopic and spectroscopic techniques
Zhongxiu Jin Jie Sheng Yubing Sun 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(3):1979-1986
Graphene oxide (GO) was synthesized using the modified Hummers method and characterized by XRD and FTIR. The sorption of 60Co(II) on GO as a function of contact time, pH, polyacrylic acid, ionic strength, temperature and solution concentration was studied by batch technique. The sorption kinetics indicated that the sorption of 60Co(II) on GO could be simulated by the pseudo-second-order model very well. The maximum sorption capacities of GO for 60Co(II) calculated from Langmuir model at pH 6.40 and T = 300 K was ~62.0 mg/g. The thermodynamic parameters from the temperature-dependent sorption isotherms indicated that the 60Co(II) sorption on GO was an endothermic and spontaneous process. The interaction mechanism between GO and Co(II) were outer-sphere surface complexation or ion exchange at pH <7, whereas the inner-sphere surface complexation was observed at pH 7–9 in terms of the analysis of XPS spectra. 相似文献
994.
Simultaneous determination of nine lignans from Schisandra chinensis extract using ultra‐performance liquid chromatography with tandem mass spectrometry in rat plasma,urine, and gastrointestinal tract samples: Application to the pharmacokinetic study of Schisandra chinensis
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You‐Jin Kim Hee Ju Lee Chul Young Kim Sun‐Young Han Young‐Won Chin Young Hee Choi 《Journal of separation science》2014,37(20):2851-2863
The fruit of Schisandra chinensis is a well‐known herbal medicine and dietary supplement due to a variety of biological activities including antihepatotoxic and antihyperlipidemic activities. However, the simultaneous validation methodology and pharmacokinetic investigation of nine lignans of S. chinensis extract in biological samples have not been proved yet. Thus, the present study was undertaken to develop the proper sample preparation method and simultaneous analytical method of schisandrol A, gomisin J, schisandrol B, tigloylgomisin H, angeloylgomisin H, schisandrin A, schisandrin B, gomisin N, and schisandrin C in the hexane‐soluble extract of S. chinensis to apply for the pharmacokinetic study in rats. All intra‐ and interprecisions of nine lignans were below 13.7% and accuracies were 85.1–115% and it is enough to evaluate the pharmacokinetic parameters after both intravenous and oral administration of hexane‐soluble extract of S. chinensis to rats. 相似文献
995.
Identification and analysis of alkaloids in cortex Phellodendron amurense by high‐performance liquid chromatography with electrospray ionization mass spectrometry coupled with photodiode array detection
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Xiaoyan Xian Bohang Sun Xueting Ye Guanying Zhang Pengyi Hou Huiyuan Gao 《Journal of separation science》2014,37(13):1533-1545
Alkaloids from Cortex Phellodendron amurense Rupr. were identified to determine the material basis for the bioactivity of this herb. HPLC–ESI‐MS with photodiode array detection coupled to XCharge C18 column was applied to analyze the alkaloids qualitatively and quantitatively. A total of 37 alkaloids were identified and tentatively characterized from the ethanol extract by online ESI‐MSn fragmentation and UV spectral analysis. A total of ten alkaloids, including four novel natural products, were tentatively identified for the first time in P. amurense. The fragmentation pathways for certain compounds were analyzed. The contents of a pair of isomers (columbamine and jatrorrhizine) and four main alkaloids (phellodendrine, magnoflorine, berberine, and palmatine) were simultaneously quantified using the aforementioned method. Results showed that the newly discovered and known components of P. amurense were helpful in determining the material basis for the bioactivity of the herb. The application of the XCharge C18 column is a suitable and practical method for the isolation of alkaloids in plants. 相似文献
996.
Qilong Xie Shuhui Liu Yingying Fan Jianzhi Sun Xiaoke Zhang 《Analytical and bioanalytical chemistry》2014,406(18):4563-4569
A selective and low organic-solvent-consuming method of sample preparation combined with high-performance liquid chromatography with diode-array detection is introduced for analysis of phthalic acid esters in edible oils. Sample treatment involves initial liquid–liquid partitioning with acetonitrile, then QuEChERS cleanup by dispersive solid-phase extraction with primary secondary amine as sorbent. Preconcentration of the analytes is performed by ionic-liquid-based dispersive liquid–liquid microextraction, with the cleaned-up extract as disperser solvent and 1-hexyl-3-methylimidazolium hexafluorophosphate as extraction solvent. Under the optimized conditions, correlation coefficients (r) were 0.998–0.999 and standard errors (S y/x ) were 2.67–3.37?×?103 for calibration curves in the range 50–1000 ng g?1. Detection limits, at a signal-to-noise ratio of 3, ranged from 6 to 9 ng g?1. Intra-day and inter-day repeatability, expressed as relative standard deviation, were in the ranges 1.0–6.9 % and 2.4–9.4 %, respectively. Recovery varied between 84 % and 106 %. The developed method was successfully used for analysis of the analytes in 28 edible oils. The dibutyl phthalate content of four of the 28 samples (14 %) exceeded the specific migration limit established by domestic and international regulations. Figure
? 相似文献
997.
Lihong Lin Wei Yu Yanan Pang Changsong Sun Qinghe Meng Xiaolei Li Xingjie Guo 《Analytical and bioanalytical chemistry》2014,406(22):5521-5526
A simple, sensitive, and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed for determination of pyraoxystrobin in rat plasma and applied to a toxicokinetics study. The separation was performed by gradient elution on a Luna 5 μ C18 (2) 100 Å column (50?×?4.6 mm I.D., 5 μm) with mobile phase: water (0.1 % formic acid, v/v)/acetonitrile (0.1 % formic acid, v/v), followed by quantification with a mass detector in multiple reaction monitoring (MRM) mode using ESI as an interface. The calibration curve was linear over a concentration range of 1.00–200 ng/mL. The recovery for pyraoxystrobin ranged from 101.4 to 108.2 %. The intraday bias and precision ranged from ?9.3 to 8.1 % and from 0.7 to 8.4 %, respectively, and the interday bias and precision ranged from ?0.3 to 4.0 % and from 4.4 to 7.2 %, respectively. The toxicokinetics of pyraoxystrobin after single 100 and 1,000 mg/kg oral doses were studied in rats. Figure
The chromatogram of pyraoxystrobin highest calibration standard (ULOQ) extract. 相似文献
998.
Copper‐Catalyzed NH Insertion and Oxidative Aromatization Cascade: Facile Synthesis of 2‐Arylaminophenols
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Dong Ding Xiaobing Lv Dr. Jian Li Guangyang Xu Dr. Bing Ma Prof. Dr. Jiangtao Sun 《化学:亚洲杂志》2014,9(6):1539-1542
A copper‐catalyzed cascade reaction of N‐H insertion and oxidative aromatization has been developed. 2‐Arylaminophenols have been prepared in moderate to high yields from the diazo substrates. Moreover, this newly established methodology allows efficient access to natural 1‐oxygenated carbazole alkaloids, such as glycozolicine and murrayafoline A. 相似文献
999.
A Highly Selective and Sensitive Turn-On Fluorescent Chemosensor Based on Rhodamine 6G for Iron(III)
Zhi-Qiang Hu Ying-Ying Gu Wen-Zhou Hu Lei-Li Sun Jiang-Hua Zhu Yi Jiang 《ChemistryOpen》2014,3(6):264-268
Recently, more and more rhodamine derivatives have been used as fluorophores to construct sensors due to their excellent spectroscopic properties. A rhodamine-based fluorescent and colorimetric Fe3+ chemosensor 3’,6’-bis(ethylamino)-2-acetoxyl-2’,7’-dimethyl-spiro[1H-isoindole-1,9’-[9H]xanthen]-3(2H)-one (RAE) was designed and synthesized. Upon the addition of Fe3+, the dramatic enhancement of both fluorescence and absorbance intensity, as well as the color change of the solution, could be observed. The detection limit of RAE for Fe3+ was around 7.98 ppb. Common coexistent metal ions showed little or no interference in the detection of Fe3+. Moreover, the addition of CN− could quench the fluorescence of the acetonitrile solution of RAE and Fe3+, indicating the regeneration of the chemosensor RAE. The robust nature of the sensor was shown by the detection of Fe3+ even after repeated rounds of quenching. As iron is a ubiquitous metal in cells and plays vital roles in many biological processes, this chemosensor could be developed to have applications in biological studies. 相似文献
1000.
Zhiwei Men Wenhui Fang Shenghan Wang Zhanlong Li Chenglin Sun Xiaojun Wang 《Journal of Raman spectroscopy : JRS》2015,46(4):388-391
The polarized Raman spectra of the upper part of a thin ice Ih film were obtained in the range of 150 cm−1 to 3800 cm−1. The spectra showed clear polarization dependence; several new peaks were also observed. The longitudinaloptic–tranverseoptic (LO–TO) splitting of the mode near 220 cm−1 in the translational vibration region was experimentally confirmed at 133 K. The Fermi resonance between the bending overtone (around 3270 cm−1) and symmetry stretching fundamental (around 3350 cm−1) in the stretching vibration region appeared at nearly the same temperature. Results showed that ice XI (i.e. proton‐ordered phase of ice Ih) slowly formed in the upper part of a thin ice Ih film without KOH as the temperature gradually decreased below 133 K. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献