A Rapid Method for Qualitative and Quantitative Analysis of Major Constituents in Dengzhanxixin Injection by LC-DAD-ESI–MSn

For the first time a rapid method for qualitative and quantitative analysis of constituents in Dengzhanxixin injection was established by liquid chromatography with electrospray ionization–tandem mass spectrometry. Eighteen compounds including flavonoids and phenolic acids were characterized or tentatively identified. Ten of these compounds, including 5-O-caffeoylquinic acid, caffeic acid, 1,3-O-dicaffeoylquinic acid, 6′-O-caffeoylerigeroside, scutellarin, 3,4-O-dicaffeoylquinic acid, 3,5-O-dicaffeoylquinic acid, erigoster B, apigenin-7-O-glucuronide and 4,5-O-dicaffeoylquinic acid, were further quantified as marker substances by LC-DAD using a C₁₈ column at 0.4 mL min^?1 within 37 min. The quantitative method was validated for ten interesting compounds, including linearity, accuracy, precisions, LOQ and LOD, which was proved to be sensitive, reproducible and accurate. The study might provide a comprehensive method for the quality assessment of dengzhanxixin injection.     

An LC-MS-MS Method for the Determination of Perfluorinated Surfactants in Environmental Matrices

Recently, there has been increasing concern about perfluorinated surfactants, especially perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) due to their persistence and chronic toxicity in the aquatic environment. Solid phase extraction (SPE) followed by liquid chromatography coupled with tandem mass spectrometry (LC-MS-MS) are widely applied to quantitatively identify PFOS and PFOA. However, the application of this powerful analytical technique is limited by matrix susceptibility. The co-eluting matrix components in the SPE extracts affect the ionization efficiency and lead to erroneous results. An efficient sample clean-up method was developed in this study to significantly remove co-eluting matrix components by applying the SPE extracts onto a silica cartridge. It was shown that matrix effect (ME%) increased to >70% for both PFOS and PFOA in the analysis of raw sewage. Internal standardization was used to further compensate for the matrix effect, which also proved to improve the signal reproducibility. The clean-up method described in this study was applied to different water samples (surface water and wastewater) to evaluate the efficiency of silica clean-up and the influence of sample origin on the matrix effect. ME% and recovery efficiency (RE%) were in the range of 91.9–98.3% and 89.2–98.0%, respectively. Results showed that the developed method is robust and can be applied to analyze PFOS and PFOA in different environmental matrices.     

Determination of Trace Amounts of Chlorogenic Acid and Three of Its Metabolites Using Time-Resolved LPME and LC-UV Detection in Biological Specimens

Chlorogenic acid (CGA) is an effective antitumor, anti-inflammatory and antimicrobial agent. Since the absorption and metabolism of CGA remains controversial, time-resolved binary-solvent synergy liquid-phase microextraction (TRBSS-LPME) using hollow fiber was developed for the extraction of CGA and its metabolites: caffeic acid, p-hydroxycinnamic acid and ferulic acid, from biological specimens. In this technique, the target drugs were extracted into a binary-solvent immobilized in the wall pores of hollow fiber. The extraction occurred due to a pH gradient between the two sides of the fiber. After extraction, an aliquot was analyzed by LC. Under the optimal conditions, the CGA, caffeic acid, p-hydroxycinnamic acid and ferulic acid had good correlation of determination values (R > 0.97) and the detection limits (LODs) were 1.0, 1.0, 2.0, and 5.0 ng mL^?1 in plasma; and 1.0, 50, 10, and 50 ng mL^?1 in urine. The mean recoveries in plasma were 90.8–119.8% for CGA and its metabolites: caffeic acid, p-hydroxycinnamic acid and ferulic acid evaluated and the mean recoveries of caffeic acid and p-hydroxycinnamic acid in urine were 81.6–111.6%. Finally, TRBSS-LPME was successfully used for the determination of target drugs in biological specimens. It not only extended the linear range of CGA determination in biological samples and improved the sensitivity, but also eliminated interferences from complex constituents in the biological specimens and reduced the LOD.     

A highly efficient synthetic method for the preparation of 3,4-dimethylbenzaldehyde from o-xylene in aqueous media

In this study, 3,4-dimethylbenzaldehyde was obtained in 82.3% total yield by oxidation of 3,4-dimethylbenzyl chloride with NaNO₃/AcOH catalyzed by PEG-600 in aqueous media. The starting material 3,4-dimethylbenzyl chloride was prepared by chloromethylation of o-xylene in CTAB micellar catalytic system. Compared with other synthetic methods, this method not only enhanced the yield, but also afforded an efficient work-up procedure. The structures of the products were confirmed by Elemental analysis, ¹H NMR and ¹³C NMR or compared with authentic samples.     

Empirical line parameters of methane in the 1.63–1.48 μm transparency window by high sensitivity Cavity Ring Down Spectroscopy

The positions and intensities of methane in the 1.58 μm transparency window have been measured by high sensitivity Cavity Ring Down Spectroscopy at room temperature. The achieved sensitivity allowed measuring intensities as small as 3 × 10⁻²⁹ cm/molecule i.e. three orders of magnitude smaller than the intensity cut off of the HITRAN line list of methane. The complete list contains a total of 16,149 transitions between 6165 and 6750 cm⁻¹. Their intensity values vary over six orders of magnitude from 1.6 × 10⁻²⁹ to 2.5 × 10⁻²³ cm/molecule. Transitions due to CH₃D in “natural” abundance in our methane sample were identified using a new spectrum of CH₃D recorded separately with a Fourier Transform spectrometer. From simulations of the CH₃D and methane spectra at low resolution, the CH₃D isotopologue has be found to contribute by up to 30% of the absorption near 1.58 μm.     

介孔Co3O4-CeO2复合氧化物的制备及在CO选择性氧化中的应用

以硝酸钴和硝酸铈为前驱物，SBA-15为硬模板，利用双溶剂法制备了Co3O4-CeO2介孔复合氧化物，通过X-射线衍射、N2吸脱附测试、程序升温还原和透射电子显微镜等技术对活性组分及载体进行了表征，并且与浸渍法和共沉淀法所制备的催化剂进行了对比分析。结果表明，相比于浸渍法和共沉淀法，采用双溶剂法制备的介孔Co3O4-CeO2复合氧化物具有均匀的介孔结构、较小的颗粒尺寸、较大的比表面积和较高的活性组分分散度。此外，CO氧化脱除评价显示与常规的共沉淀法和浸渍法所制备的催化剂相比该介孔复合氧化物具有较高的反应活性和选择性，其高活性主要归因于较高的比表面积和活性组分的高分散度。     

Titanium complexes bearing aromatic-substituted β-enaminoketonato ligands: Syntheses, structure and olefin polymerization behavior

A series of titanium complexes [(Ar)NC(CF₃)CHC(R)O]₂TiCl₂ (4b: Ar = -C₆H₄OMe(p), R = Ph; 4c: Ar = -C₆H₄Me(p), R = Ph; 4d: Ar = -C₆H₄Me(o), R = Ph; 4e: Ar = α-Naphthyl, R = Ph; 4f: Ar = -C₆H₅, R = t-Bu; 4g: Ar = -C₆H₄OMe(p); R = t-Bu; 4h: Ar = -C₆H₄Me(p); R = t-Bu; 4i: Ar = -C₆H₄Me(o); R = t-Bu) has been synthesized and characterized. X-ray crystal structures reveal that complexes 4b, 4c and 4h adopt distorted octahedral geometry around the titanium center. With modified methylaluminoxane (MMAO) as a cocatalyst, complexes 4b-c and 4f-i are active catalysts for ethylene polymerization and ethylene/norbornene copolymerization, and produce high molecular weight polyethylenes and ethylene/norbornene alternating copolymers. In addition, the complex 4c/MMAO catalyst system exhibits the characteristics of a quasi-living copolymerization of ethylene and norbornene with narrow molecular weight distribution.     

An investigation of the microstructure,optical and electrical properties of ZITO thin film using the sol–gel method

The multi-compound ZITO transparent conductive oxide (TCO) thin films were synthesized using the sol–gel method. The ZITO thin films with various volume ratios of ZnO to ITO (1:1, 2:1 and 9:1) were crystallized at different temperatures (600–700 °C). The results showed that the crystalline characteristics and optical transmittance were mainly dependent on ITO content and crystallization. Notably, the 650 °C Z₉ITO film not only had better conductivity but also possessed excellent optical transmittance. In addition, the surface roughness of the ZITO films and optoelectric properties of IZO (indium doped ZnO) films were analyzed to confirm the contribution of indium dopants on the optical transmittance. Also, the ZITO films were subjected to the effects of indium and tin dopants and this improved the related characteristics of ZnO films.     

Determination of cadmium with a sequential injection lab-on-valve by anodic stripping voltammetry using a nafion coated bismuth film electrode

This work exploited a sequential injection lab-on-valve (LOV) system for the determination of cadmium by anodic stripping voltammetry (ASV). A miniaturized electrochemical flow cell (EFC) was fabricated in LOV, in which a nafion coated bismuth film electrode was used as working electrode. The cadmium was electrodeposited on the electrode surface in bismuth solution, and measured with the subsequential stripping scan. Under optimal conditions, the proposed system responded linearly to cadmium concentrations in a range 2.0-100.0 μg L⁻¹. The detection limit of this method was found to be 0.88 μg L⁻¹. By loading a sample volume of 800 μL, a sampling frequency of 22 determinations h⁻¹ was achieved. The repeatability expressed as relative standard derivation (R.S.D.) was 3.65% for 20 μg L⁻¹ cadmium (n = 11). The established method was applied to analysis of trace cadmium in environmental water samples and the spiked recoveries were satisfactory.     

Carbon nanotubes-assisted polyacrylamide gel electrophoresis for enhanced separation of human serum proteins and application in liverish diagnosis

The application of pore-gradient polyacrylamide gel electrophoresis (PG-PAGE) incorporated with carbon nanotube modified by Triton X-100 and carboxylation so as to improve the separation of human serum proteins is reported. The novel PG-PAGE was made by adding water-soluble single-walled carbon nanotubes (CNTs) when preparing the polyacrylamide gel. Significant improvements in separation of complement C3 protein and haptoglobin (Hp) in human serum were achieved. It was estimated that the interactions between the hydrophilic groups on the proteins and the surface of the CNTs result in different adsorption kinetics of complement C3 and Hp subtype on the nanoparticles incorporated in the gel, thus enhancing the separation of the two proteins in serum. This new CNT matrix-assisted PG-PAGE method for enhanced separation of complement C3 and Hp in human serum was successfully applied to distinguish the samples from liverish patients and healthy people.