Jun 2006, Volume 1 Issue 2

  • Select all
  • Hongwei Chen, Rolf Brandt, Rolf Bandur, Thorsten Hoffmann
    In this contribution, iodine chemistry in the Marine Boundary Layer (MBL) is introduced. A series of methodologies for the measurements of iodine species in the gas and particle phases of the coastal atmosphere has been developed. Iodine species in the gas phase in real air samples has been determined in two field campaigns at the west coast of Ireland, indicating that gaseous iodo-hydrocarbons and elemental iodine are the precursors of new particle formation. Particulate iodine speciation from the same measurement campaigns show that the non-water-soluble iodine compounds are the main iodine species during the marine particle formation. A seaweed-chamber experiment was performed, indicating that gaseous I2 is one of the important precursors that lead to new particle formation in the presence of solar light in the ambient air at the coastal tidal area.
  • Yang Guizhong, Liu Tianxi, Wang Min
    A series of fluorene-alt-benzene based conjugated main chain polymers chemically attached with alkyl side chains of different lengths on phenylene rings were designed and synthesized by a palladium catalyzed Suzuki coupling reaction. The UV-vis absorption and fluorescence spectra, thermal stability of spectral property, phase transition behavior and morphology of the synthesized polymers were investigated. With increasing the length of the alkyl side chain, the UV and fluorescence spectra exhibit an obvious blue shift compared with those of the unsubstituted polymer. The alkyl substitution improves the thermal spectral stability of the polymers due to the steric hindrance of the alkyl side chains, thus leading to efficient separation of the main chain backbones. The phase transition behavior is closely related to the length of the alkyl side chains attached on the phenylene rings. The annealed films of the polymers display characteristic nematic liquid crystalline texture. TEM observations indicate that solvent-cast thin deposits of all the polymers show typical fibrillar morphology.
  • Yang Yunyun, Hongwei Chen, Teng Jiuwei, Mu Dehai, Zhong Ming, Ma Zhiling
    In this paper, high performance liquid chromatography (HPLC) along with mass spectrometry (MS) and HPLC along with a diode array detector (DAD) was used to study the compound Ilex pubescens extract. Two ionization techniques: electro spray ionization (ESI) and atmospheric pressure chemical ionization (APCI) were used in this work. The liquid chromatograms obtained by DAD, total ion chromatograms (TIC) from positive- and negative-ion ESI-MS and the positive- and negative-ion APCI-MS were compared. The liquid chromatograms obtained by TIC from ESI-MS provided more information on chromatographic peaks than those obtained by DAD or TIC from APCI-MS. It is suggested that the fingerprints of the compound Ilex pubescens extract should be provided by the liquid chromatograms obtained by DAD together with TIC from the negative-ion ESI-MS. The molecular weights of the nine main components in an HPLC-DAD chromatogram were determined by the corresponding positive- and negative-ion ESI and the positive- and negative-ion APCI mass spectra information. In the liquid chromatogram obtained by TIC from the negative-ion ESI-MS, the molecular weights of 23 main components were determined based on the corresponding positive- and negative-ion ESI mass spectra information.
  • Dong Jinyong
    Functionalization of polyolefins is an industrially important yet scientifically challenging research subject. This paper summarizes our recent effort to access structurally well-defined functional polypropylenes via transition metal-mediated olefin polymerization. In one approach, polypropylenes containing side chain functional groups of controlled concentrations were obtained by Ziegler-Natta-catalyzed copolymerization of propylene in combination with either living anionic or controlled radical polymerization of polar monomers. The copolymerization of propylene with 1,4-divinylbenzene using an isospecific MgCl2-supported TiCl4 catalyst yielded polypropylenes containing pendant styrene moieties. Both metalation reaction with n-butyllithium and hydrochlorination reaction with dry hydrogen chloride selectively and quantitatively occurred at the pendant reactive sites, generating polymeric benzyllithium and 1-chloroethylbenzene species. These species initiated living anionic polymerization of styrene (S) and atom transfer radical polymerization (in the presence of CuCl and pentamethyldiethylenetriamine) of methyl methacrylate (MMA), respectively, resulting in functional polypropylene graft copolymers (PP-g-PS and PP-g-PMMA) with controllable graft lengths. In another approach, chain end-functionalized polypropylenes containing a terminal OH-group with controlled molecular weights were directly prepared by propylene polymerization with a metallocene catalyst through a selective aluminum chain transfer reaction. Both approaches proved to be desirable polyolefin functionalization routes in terms of efficiency and polymer structure controllability.
  • Yu Caili, Zhang Faai
    Rosin glycerin ester and its bromide were prepared from natural renewable rosin, glycerin and liquid bromine which were first subjected to an esterification reaction, followed by an addition reaction. Their structures were characterized by an infrared (IR) spectrum and their thermal resistance was conducted with thermal gravity (TG) and differential scanning calorimetry (DSC). It showed that the bromide in the rosin glycerin ester decomposed faster than the ester; hence it may be used as fire-resistant material.
  • Wang Tingting, Wang Tingting, Zeng Heping, Zeng Heping
    N-Methyl-2-(N-ethylcarbozole)- fulleropyrrolidine and N-methyl-2- (4'-N,N- diphenylaminophenyl)- fulleropyrrolidine were synthesized by 1,3-dipolar cycloaddition under microwave irradiation, which were characterized by MS, 1H NMR, IR and UV-Vis. Photoinduced intramolecular electron transfer process from C60 moiety to carbazole moiety has been studied by nanosecond laser flash photolysis. The charge-separated state C60°--Cz°+ was observed in the near-IR region with a lifetime of 0.28 μs. The electronic spectrum of the C60-TPA was studied by using ZINDO method on the basis of the optimized geometrics with B3LYP/6-31G* program. The results show that the calculated absorption was beyond 440nm, essentially consistent with the experimental value 433 nm.
  • Wang Mingxia, Liu Zhongfang, Hu Xiaoli, Liu Shaopu, Kong Ling
    In a weak acidic medium, the reaction of some aminoglycoside antibiotics (AGs) such as kanamycin sulfate (KANA), gentamycin sulfate (GEN), and tobramycin sulfate (TOB) with acid thiazolyl bisazo dye Titan Yellow (TY) can result in the fading of TY. The maximum fading wavelength was located at 409 nm. The molar absorptivities (?/?104 l mol-1 cm-1) were 2.0, 1.5 and 2.5 for KANA, GEN and TOB, respectively. The spectral characteristics, effect factors, optimum conditions of the reaction and the influence of foreign substances were also investigated. The procedure is easy and fast. This method has high sensitivity and can be applied to the determination of commercial aminoglycoside antibiotics and serum samples with satisfactory results.
  • Tang Ruiren, Zhu Jinjuan, Luo Yiming, Yan Zier
    An important organic intermediate 4-hydroxymethylbenzophenone was synthesized by halogenation and hydrolyzation with phase transfer catalytic method using 4-methylbenzophenone as raw material and the technological conditions of reactions were investigated as well. Experimental results show that N-bromosuccinimide (NBS) is a good reagent to give 4-bromomethylbenzophenone undergoing a radical reaction with 4-methylbenzophenone with the yield of about 70.7%; 4-bromomethylbenzophenone can be hydrolyzed under basic conditions in the presence of phase transfer catalyst triethylbenzylammonium chloride for 5 h to give 4-hydrox-ymethylbenzophenone with yield of 84.4%. After the crude product is recrystallized from tetrahydrofuran (THF), the final product is obtained with purity above 99%. The structure of the titled compound is determined by infrared spectrum(IR), proton nuclear magnetic resonance (HNMR), and mass spectrum (MS) and elemental analysis (EA).
  • Su Xiaohui, Li Gang, Lin Ruisen, Kikuchi Eiichi, Matsukata Masahiko
    Mordenite composite membranes were prepared by means of coating a porous ?-alumina support with nanosized mordenite seeds followed by hydrothermal crystallization. A systematic investigation was performed on the influence of several factors such as ageing of the reaction mixture, alkalinity, salt addition and temperature on the formation of a mordenite membrane on the seeded support. The ageing of the reaction mixture reduces the growth rate of mordenite crystal along a-axis and b-axis but hardly influences the growth rate along c-axis. As a result, the boundaries between the surface crystals become a little larger with prolonging the period of ageing time. The growth rate of the mordenite crystal along individual axes increases first and then decreases with increasing concentration of sodium hydroxide. A higher alkalinity is unfavorable for the formation of a continuous mordenite membrane. The addition of salt in the reaction mixture has different effect on the growth rate of the mordenite crystal along each axis. With increasing the amount of salt, there was hardly influence on the growth rate along c-axis, whereas an obvious decline was observed in the growth rate along either a-axis or b-axis, which enlarges the boundaries between the surface crystals. The growth rate of the mordenite crystal increases more along c-axis than that along a-axis or b-axis with increasing temperature for hydrothermal crystallization. The use of a temperature as high as 473 K produces a membrane composed of bar-like crystals with larger boundaries.
  • Wu Zhaoyang, Zhang Xiaolei, Yang Yunhui, Shen Guoli, Yu Ruqin
    A sensitive nicotine sensor based on a molecularly imprinted electropolymer of o-aminophenol is proposed and its configuration and performance are studied in detail. On the condition of weak acidity, the sensitive layer was prepared by electropolymerization of o-aminophenol on a gold electrode in the presence of the template (nicotine). The sensor exhibits good selectivity and sensitivity to nicotine. The determination limit is 2.0×10-7 mol/L and a linear relationship between the current and concentration is found in the range of 4.0×10-7 ~ 3.3 ×10-5 mol/L. The sensor has also been applied to the analysis of nicotine in tobacco samples with recovery rates ranging from 99.0 % to 102 %.
  • Sun Ting, Zhu Tiejun, Zhao Xinbing
    Chemical and physical reactions during the low temperature aqueous chemical synthesis of nanostructured Bi2Te3 powders were investigated in-situ by pH measurement, color observation of the solution and X-ray diffraction analysis of the powders. It was found that Bi2Te3 could be synthesized only in a strong alkaline solution. Bi2Te3 nanocapsules were synthesized by the aqueous chemical route at 65 °C with the addition of disodium ethylenediaminetetraacetate salt. High-resolution transmission electron microscopy observation indicates that the nanocapsules are hollow-structured with a wall thickness of about 6 nm.
  • Yu Wanying, Zhang Hua, Huang Weidong, Chen Jiping, Liang Xinmiao
    Gas chromatography/quadrupole mass spectrometry (GC/qMS), gas chromatography/Fourier transform infrared spectrometry (GC/FTIR) and gas chromatography/orthogonal acceleration time-of-flight mass spectrometry (GC/oaTOFMS) were applied to analyze the volatile oil from the stem of Acanthopanax Senticosus (Rupr. et Maxim.) Harms. Based on the mass spectra search function of GC/qMS with the aid of the discriminability of the geometrical isomer by GC/FTIR and the ability to determine the accurate mass charge ratio (m/z) by GC/oaTOFMS, 68 GC eluants were identified successfully. Compared with the results obtained by GC/qMS only, the analytical results obtained by these hyphenated methods of gas chromatography are more credible.
  • Qi Wei, Yu Yanjun, He Zhimin
    The enzymatic hydrolysates of casein are so complex that there is no effective method to do quantitative analysis. The common techniques, such as high performance chromatography and SDS-PAGE, can only carry out qualitative analysis. On the basis of membrane separation and high performance size exclusion chromatography (HPSEC), standard peptides with different molecular mass range were prepared, and the linear relationships between mass concentration of the standard peptides and the ultraviolet absorption of corresponding peak areas were established. Consequently, mass concentration of the different hydrolysates at different reaction times could be accurately calculated. The combination of chromatography and membrane separation is of great importance to the quantitative analysis of the complex hydrolysates, which can also be applied to the other macromolecular systems, such as carbohydrates.
  • Mu Jianxin, Chen Jie, Zhang Chunling, Wang Zou, Jiang Zhenhua
    Hyperbranched poly(aryl ether ketone)s were prepared by polymerization of hydroquinone (A2) and 1,3,5-tris[4-(4-fluorobenzoyl)phenoxy]benzene (B3). The gelation of hyperbranched poly(aryl ether ketone)s was effectively avoided. Hydroxyl-terminated (HPAEK-OH) and fluoro-terminated (HPAEK-F) hyperbranched poly(aryl ether ketone)s were prepared by using different A2/B3 mass ratio. The structure of the B3 monomer was confirmed by MS, 1H NMR/IR. The glass transition temperatures of the HPAEK-F and HPAEK-OH are 114 °C and 162 °C respectively. Thermal stability of HPAEK-F is higher than HPAEK-OH.
  • Zhou Dawei, Li Famei
    The interaction between 18-methyl norethindrone and ketoprofen, including the displacement of ketoprofen from human serum albumin binding sites, was investigated by the capillary electrophoresis-frontal analysis method (CE-FA) at room temperature. A very large sample plug was introduced hydrostatically into the capillary (65 cm ? 50 μm i.d.; effective length of 35 cm) over 80 s at a height difference of 11 cm. The working conditions for CE-FA separation are as follows: operating voltage, 10 kV; running buffer, 67 mmol·L-1 phosphate, pH 7.4. The unbound ketoprofen concentration was directly measured from the height of the frontal peak. When the concentration of 18-methyl norethindrone was increased from 0 to 200 μmol/L, the unbound ketoprofen concentration was found to increase from 22.4 to 26.4 μmol/L at 100 μmol/L total ketoprofen concentration and from 82.1 to 106.2 μmol/L at 200 μmol/L total ketoprofen concentration. From these data, it may be deduced that the administration of high concentration of 18-methyl norethindrone can displace ketoprofen from its secondary binding site.
  • He Jianfeng, Liu Lan, Yang Guilan, Deng Qinying
    The uniform-sized spherical molecularly imprinted polymers were successfully prepared through molecular imprinting technology by two-step seed swelling and mini-emulsion polymerization in the aqueous condition using quinine as template molecules and methacrylic acid (MAA) as functional monomer. The polymers were characterized by IR spectra, thermal-weight analysis, scanning electron microscope and laser particle size analysis. The properties of imprinted polymers were investigated in different organic phases and aqueous media. In the organic media, results suggested that polar interactions (hydrogen bonding, ionic interactions) between acidic monomer/polymer and template molecules are mainly responsible for the binding and recognition; whereas in the aqueous medium, a considerable recognition effect was also obtained where the ionic (electrostatic) interaction and hydrophobic interaction play an important role. The experiments of binding different substrates indicated that the MIPs possessed an excellent rebinding ability and inherent selectivity to quinine.
  • Luo Jinwen, Li Huilin, Zhu Hailin
    The characteristics of bias caused by split-flow electrokinetic injection (SEKI), a new type of sample injection method used in coupled flow injection capillary electrophoresis system (FI CE), was investigated using pseudoephedrine hydrochloride, a basic drug, and ibuprofen, an acidic drug, as model analytes. It was found that bias imposed by SEKI under the condition of continuous sample matrix/running buffer was similar to that done by electrokinetic injection (EKI). The linearity of calibration curve provided by SEKI was similar to that offered by non-bias hydrodynamic injection (HDI) but significantly better than that obtained by EKI. These features were exploited to improve analytical performances in simultaneous determination of the minor ingredient of pseudoephedrine hydrochloride and the major ingredient of ibuprofen in a pharmaceutical preparation. Detectability of 0.7 mg/l for pseudoephedrine hydrochloride was achieved at a sample throughput rate of 24 times per hour, which is 30% lower than that obtained by HDI-based conventional CE. Relative standard deviations (RSDs) of 2.8% for the minor ingredient and 1.2% for the major ingredient were produced in 11 runs of a test solution containing 13.1 mg/l pseudoephedrine hydrochloride and 81.4 mg/l ibuprofen. This is an improvement compared to that obtained by HDI-based conventional CE. Analytical results for two batches of compound ibuprofen tablets by the SEKI-based FI CE approach were in good agreement with that obtained by a conventional high performance liquid chromatographic method.
  • Wang Yan, Yao Lijuan, Zhao Pengcheng, Wang Jinghan, Wang Yanji
    A method for identifying the writing age of blue ballpoint pen ink has been established due to the imperative demand in forensic laboratories. The content of the volatile components in blue ballpoint pen ink were determined by gas chromatography (GC). The absorbance of dye in blue ballpoint pen ink was measured by UV Vis spectrometry A writing age curve of the ink was established using the ratio of the content of the volatile components to the dye, based on the identification of 74 kinds of blue ballpoint pen ink of domestic and international origins. The change of benzene alcohol or phenoxetol with the writing age was also tested. Different kinds of blue ballpoint pen ink were detected and the repeatability of the experiment was investigated. The results indicate that the method is reliable, sensitive, systematic and is especially suitable for practical use.
  • Li Manmei, Liu Zhong, Zhang Zhulin, Ma Lin
    In this paper, curcumin, demethoxycurcumin, bisdemethoxycurcumin and another curcumin derivative are investigated for their inhibitory effects on nonenzymatic glucosylation in vitro, their binding reaction with bovine serum albumin (BSA) and their influence on the conformational changes of BSA. It demonstrated that all of these curcumin derivatives inhibited the formation of advanced glycation end products (AGE). Curcumin showed the most potent inhibitory activity, followed by demethoxycurcumin and bisdemethoxycurcumin. Moreover, it indicated that they extensively binded to the protein and induced the conformational changes of BSA.
  • Feng Guodong, Han Songbai, Yu Aimin
    The feeding-sample system used by microwave plasma torch atomic emission spectroscopy (MPT-AES) is the pneumatic nebulization system; its efficiency, however, is not good. A newly built injector pump ultrasonic nebulizer combination feeding-sample system has been designed. Its performance was tested and compared with that of the pneumatic nebulization system. It can be concluded that the newly built feeding-sample system can increase the spectral line intensity by about two to three times and decrease the detection limit by about 2 to 10 times. Moreover, this newly built system can reduce the time taken washing the sample cell from 30 min or so to about 10 min.
  • Zhang Hao, Wang Yan, Lu Zhongbin, Liu Donghua
    A HPLC method was developed for the analysis of quizalofop-P-tefurylof in soybean. The samples were extracted with methanol-water?volume ratio, The extracts were cleaned up with a column of silica gel. The final residue was detected by HPLC, using a UV detector. The recoveries from the analytical method for soybean were 84.32%-89.25%. Variable coefficients were 0.49%?1.51%. This method proved to be simple, reliable and accurate.