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141.
A new separation system of capillary electrophoresis for the simultaneous determination of metals by using ethylenediamine tetraacetic acid (EDTA) as complexing agent and employing vancomycin as complex selector was described. The Z-shape cell capillary electrophoresis was used to enhance the sensitivity for the determination of the complexes of Cu(Ⅱ), Ni(Ⅱ), Co(Ⅱ) and Fe(Ⅲ) with EDTA. The partial filling method (co-current mode) was used in order to increase the selectivity of the electrophoretic method, meanwhile vancomycin was not present at the detector path during the detection of metal-EDTA complexes. The vancomycin concentration, phosphate concentration and pH of the buffer strongly influenced mobility, resolution and selectivity of the studied analytes. Under the optimal condition, the relative standard deviations (n=5) of the migration time and the peak area were less than 3.14% and 7.35%, respectively. Application of the Z-shape cell capillary electrophoresis method with UV detection and vancomycin loading led to the reliable determination of these metal ions in tap water and the recoveries were 97%-101%. The detection limits based on a signal to noise ratio of 3 : 1 were found in the range of 2-10 μg·L^-1. 相似文献
142.
Mao-fengZhang Qiao-hongYao Chun-huiHuang Wei-xiaoCao 《高分子科学》2005,(1):27-27
A kind of azo-containing resin (Azo-R) was synthesized by a simple way through the coupling reaction of 2-nitro-N-methyldiphenylamine-4-diazoresin (NDR) with phenol, and a new covalentely attached multilayer film from Azo-R as H-donor and photosensitive diazoresin, diphenylamine-4-diazoresin (DR) as H-acceptor via H-bonding attraction by selfassembly technique has been fabricated. Following the decomposition of diazonium group of DR under exposure to UV light, the H-bonds between the layers of the film convert to covalent bonds and the film becomes very stable toward polar solvents or electrolyte aqueous solutions. Thus the UV-irradiated azo-containing films can be used to measure photocurrent in a conventional three-electrode photoelectrochemical cell using KCl as supporting electrolyte. It was confirmed that the azo-containing multilayer film is responsible for the photocurrent generation. 相似文献
143.
建立了超高效液相色谱-串联质谱(UHPLC-MS/MS)快速同时测定生姜中姜辣素类和姜黄素类营养成分的分析方法,具体包括6-姜酚、8-姜酚、10-姜酚、6-姜烯酚、8-姜烯酚、10-姜烯酚、四氢姜黄素、姜黄素、去甲氧基姜黄素、双去甲氧基姜黄素10种目标物。采用ZORBAX RRHD Eclipse Plus C18色谱柱(100 mm×2.1 mm,1.8 μm)分离,以0.1%(v/v)甲酸水溶液和0.1%(v/v)甲酸甲醇溶液为流动相进行梯度洗脱,采用电喷雾电离(ESI)源、正离子和多反应监测(MRM)模式对目标物进行定性确证和定量分析。10种营养成分的线性相关系数(r)均≥ 0.9995,方法的定量限为0.10~7.71 μg/L,样品基质在3个水平下的平均加标回收率为82.8%~115.3%,相对标准偏差(RSD)为0.58%~11.49%。分析结果显示,生姜中10种营养成分均有检出,其中6-姜酚的含量最高且集中分布于373.35~702.48 mg/kg。该法简便快速,准确可靠,适用于生姜中姜辣素类和姜黄素类营养成分的分析,可为生姜质量鉴定和控制提供技术手段。 相似文献
144.
X. N. Yang 《Journal of solution chemistry》1998,27(3):261-272
A diaphragm cell has been used to measure mutual diffusion coefficients at 25°C for four binary nonelectrolyte mixtures: ethylbenzene + n-hexane, carbon tetrachloride + ethylbenzene, cyclohexane + p-xylene, and 1,2-dichloroethane + cyclohexane. A free-volume predictive approach for binary mutual diffusion coefficients was developed and tested. Only infinite dilution diffusion coefficients, some readily available pure substance data, and UNIFAC group contribution parameters are used in the model. No binary equilibrium thermodynamic information is required. For 73 binary systems with an overall average absolute deviation of 5.2%, it has been shown that the developed method is better than two commonly available reference methods for the prediction of liquid diffusion coefficients. 相似文献
145.
采用一步种子溶胀聚合法制备了颗粒呈单分散的交联聚甲基丙烯酸环氧丙南树脂,对其环氧基的组成比进行了表征,并以氨基葡萄糖为配基,首次制备了纯化粗品伴刀豆球蛋白-A(Ⅲ)(Con-A,Ⅲ)的聚合物基质的高效亲合色谱柱。配基在树脂上的键合量为8.2mg/g,对纯化后的Con-A(Ⅲ)的吸附量为13.4mg/g。使用该亲合色谱介质成功地从粗品Con-A中快速纯化了Con-A,电泳分析显示为一个主要的谱带,纯度从15%提高到95%。 相似文献
146.
Suitable analytical methodologies were developed allowing direct determination of As, Cu, Fe, Pb, Sb and Sn in alcohol fuel samples by electrothermal atomic absorption spectrometry. Different chemical modification approaches were tested and compared in terms of analytical performance and in practical terms. Experimental conditions were optimized allowing little sample dilution and use of calibration curves prepared with aqueous inorganic analyte standards. Methodologies were tested with analyte spiked alcohol samples. Good analyte recoveries from spiked alcohol samples, precision better than 10% and limits of detection in the sub μg l−1 range were achieved. 相似文献
147.
A comparison of different nebulisers for direct hyphenation of capillary and nano liquid chromatography (Cap-LC, Nano-LC) and quadrupole-based collision cell inductively coupled plasma mass spectrometry (CC-ICP–MS) for phosphorylation profiling of tryptic protein digests is described. Helium was used as cell gas and specially tuned instrumental conditions were used to achieve background minimisation at the mass of phosphorus, because of kinetic energy discrimination of the interfering polyatomic ions. The proposed set-up is based on a modified capillary electrophoresis interface and a home-made 4 mL spray chamber. It enables the use of gradient conditions with a highly concentrated organic mobile phase as often used in protein phosphorylation analysis, without the need to apply membrane desolvation for removal of the organic phase or further background minimisation. No significant signal suppression or other negative effects caused by the organic mobile phase occur, because of the low flow rates used in Cap-LC and the robust plasma conditions of the CC-ICP–MS instrument. A tryptic digest of beta-casein was investigated as model compound to demonstrate the applicability of the proposed set-up for phosphorylation profiling in protein analysis using quadrupole based collision-cell ICP–MS as phosphorus-specific detector. Detection limits for phosphorylated peptides down to the sub picomole level were obtained. As a complementary technique, electrospray ionisation tandem mass spectrometry (ESI–MS–MS) with data base searching was used for further characterisation of the phosphorylated peptides detected. 相似文献
148.
149.
《中国化学快报》2020,31(5):1207-1212
Developing high efficiency and low cost electrocatalysts is critical for the enhancement of oxygen reduction reaction (ORR), which is the fundamental for the development and commercialization of renewable energy conversion technology. Herein, zinc-nitrogen-carbon (Zn-N-C) was prepared by using biomass resource chitosan via a facile carbon bath method. The obtained Zn-N-C delivered a high specific surface area (794.7 cm2/g) together with pore volume (0.49 cm3/g). During the electrochemical evaluation of oxygen reduction reaction (ORR), Zn-N-C displayed high activity for ORR with an onset potential E0 = 0.96 VRHE and a half wave potential E1/2 = 0.86 VRHE, which were more positive than those of the commercial 20 wt% Pt/C benchmark catalyst (E0 = 0.96 VRHE and E1/2 = 0.81 VRHE). In addition, the Zn-N-C catalyst also had a better stability and methanol tolerance than those of the Pt/C catalyst. 相似文献
150.
An efficient clean-up procedure coupled with a high performance liquid chromatography (HPLC) with on-line electrochemical (EC) reduction and fluorescence detection (FLD) was developed to quantify nitrated polycyclic aromatic hydrocarbons (NPAHs) in the airborne particulate. In this process, NPAHs were extracted ultrasonically followed by analysis by using a reversed phase column with an aqueous eluent containing 70% aqueous acetonitrile and sodium monocholoroacetate as a buffer solution. The extraction efficiencies were above 83% for 1-nitropyrene and 1,3-dinitropyrene (1,3-DNP) 1,6-DNP, and 1,8-DNP, and calibration graphs were linear with very good correlation coefficients (r>0.999) and the detection limits were in the range of 1.0-2.2 pg for dinitropyrenes and nitropyrene. The proposed method provides a relatively simple and convenient procedure for determining the NPAHs samples in airborne particulate. 相似文献