毛细管电泳-电感耦合等离子体原子发射光谱法对田七提取液中Fe、Cu和Mg存在状态的研究

提出了以水作溶剂微波萃取提取,并以毛细管电泳电感耦合等离子体原子发射光谱(CE-ICP-AES)法测定田七提取液中Mg、Cu和Fe的形态的分析方法。实验结果表明:Mg仅以游离态存在;而Cu和Fe除了游离态以外,还存在其它三种未知的形态。此外,还测定了田七中20个微量元素的总含量,并得到了上述待测元素在水提取液中的提取率。     

Solid-phase microextraction–capillary gas chromatography combined with microwave-induced plasma atomic-emission spectrometry for selenite determination

The use of solid-phase microextraction (SPME) with gas chromatography coupled to microwave-induced plasma atomic-emission detection (GC–MIP-AED) is described for selenite [Se(IV)] speciation. Aqueous standards were derivatised with sodium tetraethyl- or tetrapropylborate and extracted by SPME. Headspace extraction of the ethyl and propyl derivatives was studied. Relevant experimental conditions were optimised, including conditions for derivatisation and extraction and those of gas chromatographic analysis. The limits of detection achieved for headspace sampling of derivatised Se(IV) were in the low ng mL^–1 range for both ethylation and propylation. When the method was applied to analysis of selenite in selenised yeast reference material results were in good agreement with the indicated values.     

拟多维高效液相色谱法分离纯化双峰驼精清中的活性蛋白

利用一种新的高效液相色谱洗脱技术，建立了 ｐＨ缓冲液／离子对二元洗脱模式，对双峰驼精清的两种提取物的反相柱上进行了分离，得到了较纯的活性蛋白组分。该法操作简单、快速、比常规ＨＰＬＣ有更高的选择性及峰容量，并可减少活性蛋白的失活。     

Synthesis of ultrafine SiC from rice hulls (husks): A plasma process

Heat-treated rice hulls have been used as precursor material for synthesis of ultrafne SiC in a RF plasma reactor. Rice hulls containing finely distributed silica and active carbon act as a source for SiC formation. The plasma-synthesized powder contained ultrafnc -SiC with excess carbon and some unreacted silica. Post-treatment processes such as oxidation and acid (HF) treatment appear to be effective in removing the excess carbon and silica.     

Melnikov's criterion for nondifferentiable weak-noise potentials

The stationary probability density of Fokker-Planck models with weak noise is asymptotically of the form exp[–1 /(q)]. If is smooth, it satisfies a Hamilton-Jacobi equation at zero energy and can be interpreted as the action of an associated Hamiltonian system. Under this assumption, has the properties of a Liapounov function, and can be used, e.g., as a thermodynamic potential in nonequilibrium steady states. We consider systems having several attractors and show, by applying Melnikov's method to the associated Hamiltonian, that in general is not differentiable. A small perturbation of a model with differentiable leads to a nondifferentiable . The method is illustrated on a model used in the treatment of the unstable mode in a laser.     

超声雾化进样微波诱导等离子体原子吸收光谱法测定银的某些影响因素研究

本文将超声雾化技术与MIP-AAS联用,以“L”型吸收管代替“T”型吸收管作为AAS测量的吸收池,采用水冷凝和浓H_2SO_4吸收相结合去溶,研究TUSN-MIP-AAS方法测银时的某些影响因素,讨论了微波前向功率,载气流速、去溶系统、溶液酸度、共存离子及易也离元素等对吸收信号的影响,本法所得的测银的特征浓度为0.01μg/ml(328.1nm)和0.03μg/ml(338.3nm),相对标准偏差为7.5％.     

Investigation of glow discharge plasma for surface modification of polypropylene

Material surface properties of polymers, plastics, ceramics and textiles can be modified by atmospheric or low‐pressure glow discharge plasma. The aim of the present work is to study the surface modification of biaxially oriented polypropylene (BOPP) film in order to improve its hydrophilic and wetting properties. In this article we used low‐pressure, low‐temperature oxygen plasma for the surface treatment of BOPP. Scanning electron microscopy indicates that plasma treatment causes mainly physical changes by creating microcraters and roughness on the surface and increasing surface friction. Attenuated total reflectance infrared spectra show oxygen‐containing groups such as ? OH at 3513 cm^?1 and C?O at 1695 cm^?1. Microscopic investigations of water droplets on BOPP (treated, untreated) show that the interfacial adhesion of treated surfaces is increased. Copyright © 2003 John Wiley & Sons, Ltd.     

Determination of doxorubicin in human plasma by excitation-emission matrix fluorescence and multi-way analysis

Direct determination of doxorubicin (DXR), a cytotoxic anthracycline antibiotic, in human plasma was accomplished based on excitation-emission matrix (EEM) fluorescence measurements and multi-way chemometric methods based on parallel factor analysis (PARAFAC) and N-PLS. Several different procedures, such as residual analysis, core consistency diagnostic (CONCORDIA) and split-half analysis were employed to determine the correct number of factors in PARAFAC. These procedures converged to a choice of two factors, attributed to DXR and to the sum of two fluorescence species present in the plasma. Sample PARAFAC loadings were employed to build a regression model against concentration, resulting in a RMSECV of 0.060 μg ml⁻¹. N-PLS using two factors produced a RMSECV of 0.045 μg ml⁻¹. Figures of merit (FOM), such as sensitivity (SEN), selectivity (SEL) and limit of detection (L_D) were determined for both PARAFAC and N-PLS.     

Development and Validation of a Liquid Chromatographic Method for Determination of Efavirenz in Human Plasma

A simple, rapid, and sensitive high-performance liquid chromatographic method for estimation of efavirenz in human plasma has been developed and validated. Chromatography was performed with C₁₈ analytical column and 50:50 acetonitrile–phosphate buffer (pH 3.5) as mobile phase. Compounds were monitored by UV detection at 247 nm. The retention time for efavirenz was 6.45 min and that for the internal standard, nelfinavir, was 2.042 min. Response was a linear over the concentration range of 0.1 μg–10 μg mL⁻¹ in human plasma. The method was simple, specific, precise and accurate and was useful for bioequivalence and pharmacokinetic studies of efavirenz.     

安培检测芯片毛细管电泳及其初步应用

An end-channel amperometric detector with a guide tube for working electrode was designed and integrated on a home-made glass microchip. The guide tube was directly patterned and fabricated at the end of the detection reservoir, which made the fixation and alignment of working electrode relatively easy. The fabrication was carried out in a two-step etching process. A 30 μm carbon fiber microdisk electrode and Pt cathode were also integrated onto the amperometric detector. The baseline separation of dopamine (DA), catechol (CA) and epinephrine (EP) was achieved within 80 s. Relative standard deviations of not more than 5.2% were obtained for both peak currents and migration times of DA and CA (n=5). Using standard adding method, DA in tLrine and plasma samples was detected. The recoveries were in the range of 83%—103%.