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991.
Mingfei Shao Jingbin Han Wenying Shi Min Wei Xue Duan 《Electrochemistry communications》2010,12(8):1077-1080
The ordered ultrathin film based on iron(III) porphyrin and Co–Al layered double hydroxide (Co–Al LDH) nanosheets has been fabricated via the layer-by-layer (LBL) method. The film modified electrode demonstrates a couple of well-defined reversible redox peaks attributed to Co(III)/Co(II), with iron(III) porphyrin serving as an efficient mediator for facilitating the electron transfer. Furthermore, it exhibits excellent electrocatalytic behavior for H2O2 with a wide linear range of response, high sensitivity and low detection limit. 相似文献
992.
Elisana Afonso Moura Lidiane Pinto Correia Márcia Ferraz Pinto José Valdilânio Virgulino Procópio Fábio Santos de Souza Rui Oliveira Macedo 《Journal of Thermal Analysis and Calorimetry》2010,100(1):289-293
This article had studied the thermal characterization of the raw material and different fluconazole crystals, obtained through
recrystallization with different solvents using thermoanalytical techniques (TG, DTA, DSC-50, DSC Photovisual, DSC-60) and
Pyr-GC/MS. The results confirmed that the fluconazole volatilizes without decomposition until 250 °C. Pyr-GC/MS showed hexachlorobenzene
like impurities in fluconazole raw material. 相似文献
993.
994.
Jiang F Wang Y Hu X Shao N Na N Delanghe JR Ouyang J 《Journal of separation science》2010,33(21):3393-3399
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. 相似文献
995.
Fangjun Wang Guanghui Han Zhiyuan Yu Xinning Jiang Shutao Sun Rui Chen Mingliang Ye Hanfa Zou 《Journal of separation science》2010,33(13):1879-1887
It is one of the key issues to develop powerful fractionating method to increase the identification of the low‐abundance phosphopeptides. In this study, a semi‐online 2‐D LC separation strategy based on three‐step fractionation of the enriched peptides on strong anion‐exchange trap column was developed. It was demonstrated that the sensitivity and phosphoproteome coverage obtained by this fractionating method with strong anion‐exchange trap column is much higher than those by the conventional methods based on C18 trap column. In addition, when the same amount of sample was loaded, the number of identified phosphopeptides had increased 108%. Combination of this three‐step fractionation method with RPLC‐MS/MS analysis by 300 min RP‐gradient separation was applied to phosphoproteome analysis of human liver proteins, and 853 unique phosphopeptides was positively identified from 500 μg tryptic digest of human liver proteins. After three cycles' consecutive analyses, 1554 unique phosphopeptides and 1566 phosphorylated sites were totally identified from 735 phosphorylated proteins at a false discovery rate of <1% in about 54 h of analysis time. 相似文献
996.
Liang Zhu Zhong Hu Gerardo Gamez Wai Siang Law HuanWen Chen ShuiPing Yang Konstantin Chingin Roman M. Balabin Rui Wang TingTing Zhang Renato Zenobi 《Analytical and bioanalytical chemistry》2010,398(1):405-413
By gently bubbling nitrogen gas through beer, an effervescent beverage, both volatile and non-volatile compounds can be simultaneously sampled in the form of aerosol. This allows for fast (within seconds) fingerprinting by extractive electrospray ionization mass spectrometry (EESI-MS) in both negative and positive ion mode, without the need for any sample pre-treatment such as degassing and dilution. Trace analytes such as volatile esters (e.g., ethyl acetate and isoamyl acetate), free fatty acids (e.g., caproic acid, caprylic acid, and capric acid), semi/non-volatile organic/inorganic acids (e.g., lactic acid), and various amino acids, commonly present in beer at the low parts per million or at sub-ppm levels, were detected and identified based on tandem MS data. Furthermore, the appearance of solvent cluster ions in the mass spectra gives insight into the sampling and ionization mechanisms: aerosol droplets containing semi/non-volatile substances are thought to be generated via bubble bursting at the surface of the liquid; these neutral aerosol droplets then collide with the charged primary electrospray ionization droplets, followed by analyte extraction, desolvation, ionization, and MS detection. With principal component analysis, several beer samples were successfully differentiated. Therefore, the present study successfully extends the applicability of EESI-MS to the direct analysis of complex liquid samples with high gas content. Figure
By gently bubbling nitrogen gas through beer, both volatile and non-volatile compounds can be simultaneously sampled in the form of aerosol for further analysis, allowing fast chemically fingerprinting using extractive electrospray ionization mass spectrometry (EESI-MS). 相似文献
997.
Solvent polarity plays an important role in electrospray ionization-mass spectrometry (ESI-MS), one of the most widely used
analytical methods for biochemistry. To have a comprehensive understanding of how solvent polarity affects ESI-MS measurements,
we systematically investigated the polarity change in the ESI plume formed from an ethanol solution using laser-induced fluorescence
(LIF) spectroscopy. Two solvatochromic dyes (i.e., dyes whose fluorescence emission is sensitive to solvent polarity), Nile
red and DCM (4-dicyanomethylene-2-methyl-6-p-dimethylaminostyryl-4H-pyran), were used as probes. The peak emission wavelengths
of these two dyes exhibited significant red shifts (8–12 nm) when the measuring spot was moved away from the spray tip and
in radial direction in the plume, indicating a dramatic polarity change during shrinking of the droplets. The emission intensities
were also measured with a polarity-insensitive dye as a reference. The results are consistent with the peak wavelength measurements.
Two key mechanisms responsible for the change of solvent polarity in the plume were considered, water entrainment from the
surrounding air and solvent evaporation. Furthermore, quantitative analysis of the solvent polarity change was performed by
using the Lippert-Mataga polarity parameter Δf. The value of Δf reached 0.305–0.307 at the periphery of the ESI plume, which means that the solvent polarity in the smaller droplet is close
to that of a mixture of 30% water and 70% ethanol (Δf = 0.307), even though the bulk solvent was ethanol containing less than 1% water as an impurity. 相似文献
998.
Yingliang Wei Qing Zhang Chen Shao Chao Li Luping Zhang Xianli Li 《Journal of Analytical Chemistry》2010,65(4):398-403
A rapid and convenient electrochemical method is described for the determination of salbutamol based on multi-carbon nanotubes
(MWNT) film coated glassy carbon electrode (GCE). The electrochemical behavior of salbutamol at this modified electrode was studied by square wave voltammetry, which indicated
that the oxidation peak potential of salbutamol shifted on 40 mV to less positive potential and the peak current increased
4.5 fold, in contrast to that at a bare electrode. Various experimental parameters such as pH value of supporting electrolyte,
the amount of modifier, and accumulation time were optimized. Under optimal measurement conditions, there is a good linear
relationship between the peak current (I
pa) and salbutamol concentration in the range from 8.0 × 10−7 to 1.0 × 10−5 M, and the detection limit is 2.0 × 10−7 M (S/N = 3) at 2 min accumulation. The method has been successfully employed to detect salbutamol in pharmaceutical formulations. 相似文献
999.
Vinylsilafluorene (VSiF) was successfully synthesized and copolymerized with vinylcarbazole and methyl methacrylate via free radical copolymerization for the first time. The synthesis, photophysical properties, computational modeling studies, and organic light-emitting devices of the VSiF copolymers were presented. The good coordinated photoluminescent (PL) spectra with the absorption of blue light-emitting materials and the high energy band-gap of the VSiF copolymers were observed. Higher triplet band gap (3 E g) to host the blue phosphorescent emitters and better HOMO and LUMO than PVK for electron and hole injection and transportation of the VSiF model compounds were revealed by density functional theory (DFT) calculations. The preliminary device results in applications of these copolymers as host materials for green phosphorescent emitters demonstrate the copolymers of VSiF and vinylcarbazole have comparable device performance of polyvinylcarazole (PVK), suggesting a bright future of VSiF as building blocks for host materials. 相似文献
1000.