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91.
Simultaneous determination of triterpene saponins in ginseng drugs by high-performance liquid chromatography 总被引:3,自引:0,他引:3
A HPLC method for the simultaneous determination of 11 triterpene saponins with four-type aglycones (protopanaxadiol, protopanaxatriol, ocotillol and oleanolic acid types) in Ginseng drugs was developed and validated. Using a gradient of acetonitrile and 10 mM K-phosphate buffer (pH 5.80) as the mobile phase and UV detection at 196 nm, more than 18 ginsenosides with different aglycones were separated satisfactorily within 60 min. The detection limits (signal/noise> or =3) were 0.1 microg for ginsenosides Rb1, Rc, Rd, Re and Rg1, chikusetsusaponin III, and notoginsenoside R2, 0.2 microg for gisenoside Ro and chikusetsusaponin IVa, 0.3 microg for chikusetsusaponin IV, and 3 microg for majonoside R2. The calibration curve of each saponin had a correlation coefficient close to 1. Intra- and interday precisions were less than 2.1% (n=5) and 3.3% (n=15), respectively. The recovery rates of extraction were in the range of 96.4-102.7% for all ginsenosides. By adopting this method, the determinations of 11 ginsenosides in three Ginseng drugs derived from Panax ginseng, Panax vietnamensis var. fuscidiscus and Panax japonicus (Japan) were achieved. 相似文献
92.
Kun Guo YANG Rui Mao HUA* Hai WANG Bo Qing XU* Department of Chemistry Tsinghua University Key Laboratory of Organic Optoelectronics & Molecular Engineering of Ministry of Education Beijing Department of Chemistry Chemical Engineering Guangxi Normal University Guilin 《中国化学快报》2005,16(4)
Diphenylmethane and substituted diphenylmethane are important compounds forsynthesis chemistry as well as industrial chemistry. These compounds are easilysynthesized by the benzylation of aromatic compounds with benzyl chloride or benzylalcohol catalyzed by homogeneous acid catalysts, such as AlCl3, FeCl3, H2SO4, HF andBF3. However, these catalytic systems are highly corrosive, and usually proceed withlow selectivity. In addition, they are less satisfactory from the environmen… 相似文献
93.
In this paper a modified two-step procedure for synthesis of N-(1-naphthyl) suecinimide (NaS) was developed, and the molecular structure of NaS was properly characterized by XRD, FT-IR, 1H NMR, DSC, etc. The results show that the melting point of our product is 159 ℃-160.5 ℃, and the characteristic infrared absorption band of carbonyl group splits into two peaks (1705cm^-3/1779cm^-3), which are found to be quite different from the documented data (rap 147℃ -149℃; IR C=0-1700cm^-3). Besides, photophysical spectroscopy was found to be powerful to study the molecular structure and crystal morphology of NaS compound. 相似文献
94.
This paper is the study of the fluorescence enhancement of Eu3+-1-ethyl-6-fluoro-4-oxo-7-(1-piperazinyl)-1,8-naphthyridin-3-carbonic acid (enoxacin, EFLX) system by surfactants. It was
found that sodium dodecylbenzenesulfonate (SDBS) exhibits great enhancement on the fluorescence of the Eu-EFLX system. The
molar ratio is 1:2:1 for Eu:EFLX: SDBS. Under the optimum conditions, the fluorescence intensity is a linear function of europium
in the range of 1.0 × 10−8 ∼ 5.0 × 10−6 mol/L, the detection limit is 1.0 × 10−9 mol/L. The application of the Eu-EFLX-SDBS system for the determination of trace europium in rare earth samples gave satisfactory
results.
Received October 19, 2000. Revision August 10, 2001. 相似文献
95.
Methyl methacrylate and butyl methacrylate were polymerized in oil-in-water microemulsions that were stabilized by sodium dodecyl sulphate (SDS). A poly(N-acetylethylenimine) (PNAEI) macromer was also included in the recipe, as a cosurfactant and a comonomer. Polymerizations were initiated by UV-irradiation. The average diameters of latex particles, obtained by STM, were in the range of 17-200 nm. The experimental data evidenced that the particle size was mainly dependent on the SDS/PNAEI ratio. Polymerization yields were around 75-85%. The synthesized copolymers have viscosity average molecular weights in the range of 2.1-2.4×106 and glass transition temperatures of 38.0-43.5°C, lower than those obtained without using PNAEI. The investigation by means of FTIR and 1H-NMR techniques revealed that PNAEI was incorporated into the nanoparticles. 相似文献
96.
97.
A new approach to isoprostanes and neuroprostanes featuring cis-dialkyl stereochemistry at the cyclopentane ring has been developed by employing an intramolecular cross-coupling reaction of an alkyl iodide and a tethered alkenylsiloxane for stereoselective installation of a functionalized omega-side chain. 相似文献
98.
The interaction of pinacyanol chloride(PC) with nucleic acids has been investigated by a series of experiments.Extensive hypochromism,appreciable peak shifts,isosbestic points and new peaks of the product of binding to nucleic acids in the spectra were observed.They showed that the interaction between PC and nucleic acids occurred.The results from absorption spectra of DNA,DNA melting,electrophoresis and fluorescence polarization studies have indicated that PC binds to DNA in nonintercalative way.Consistent with the nonintercalation,the studies of fluorescence titration and absorption titration specified that the binding of PC to nucleic acids occurred by an outside stacking binding,in which nucleic acids served for acting templates,The fact that the new absorption peaks of bound PC at ca,485nm are just close to the absorption bands of Haggregate of PC at high concentrations without DNA further supports the outside stacking binding mode,In addition,other evidence indicated that the interaction between PC and nucleic acids is not purely electrostatic. 相似文献
99.
100.
Synthesis, Characterization and Two-Photon Absorption Properties of a Novel Pyridinium Salt 总被引:2,自引:0,他引:2
A novel pyridinium salt, 2,4-bis[p-(N,N-dimethylamino)styryll-N-metlayl pyridinium iodide (BMSPI) was synthesized and characterized by TG, ^1H NMR spectroscopy and elemental analysis, and the reaction process was studied by using ES-MS. When BMSPI was pumped by a pulsed 1064 nm, 50 ps laser beam, it manifests highly efficient TPA (Two-Photon Absorption) and up-conversion superradiance. The up-conversion efficiency was 6.0% at the pump energy of 4-6 mJ and the lifetime of two-photon fluorescence was measured as 59 ps. 相似文献