ICP-AES法直接测定阳极泥中的金和银

使用ICP－AES法同时测定了多个阳极泥样品中的金和银。加标回收率为95．4％－103．2％,10次测定的RSD为0．8％－4．8％。方法简便,速度快,结果准确。     

火焰原子吸收光谱法测定铜镍矿浮选产品中铜、镍、镁

研究了用火焰原子吸收光谱法在同一溶液体系中直接快速测定金川铜镍矿浮选产品中铜、镍、镁含量新的新方法。考察了产品中高含量的SiO2对测定镁的干扰情况，并提出了排除这项干扰简便方法，根据各元素的标准溶液系列的测定数据，推算出了铜、镍、镁3元素的线性回归方程及线性相关系数，特征浓度铜为0．40mg.L^-1/1%，镍为0．48mg.L^-1／1％，Mg为0．018mg.L^-1／1％；线性浓度范围铜，镍均为0－10mg.L^-1，镁为0．2－1．2mg.L^-1。相对标准偏差铜为2．5％(n=6)，镍为2．3％（n＝6），镁为2．8％（n=6），加标回收率铜为96．5％－102．5％，镍为98．8％－103．5％，镁为98．2％－102．5％，这种方法操作简便，快速，实用，具有较好的精密度和准确度，实际产品分析结果与外检单位及金川公司测定的结果吻合。     

微波消化-氢化物原子荧光法测定水产品中的铅

采用微波消化技术溶解水产品,以氢化物－原子荧光法测定铅,讨论并确定了最佳测定条件,结果表明,铅的测定线性范围为0－100ng/mL,方法的相对标准偏差为1．2％－5．3％,回收率为94．8％－103．5％。该方法简便、快速,用于水产品中铅的测定,获得令人满意的结果。     

免疫亲和柱HPLC荧光检测酒中黄曲霉毒素B1、B2、G1、G2

采用单隆抗体免疫样和技术作为直接从样品分离提纯黄曲霉素素的特效手段,提出液挥发干后,经衍生用HPLC荧光检测器测定,本法在样品中添加2．5μg/kg黄曲霉素素时进行10次测定,平均回收率分别为G178．3％、B197．3％、G261．7％、B290．5％;2．5μg/kg10次测定的精密度分别为：G4．50％、B13．805、G23．68％、B24．77％,本方法在25－1250pg范围内呈线性,相关系数分别为G1：r=0.9990,B1:r=0.9994,G2:r=0.9995,B2:r=0.9992 ,测定的最低检出限为6．25pg.     

ICP-AES法测定水中微量磷

用ICP－AES法测定水中磷，并确定了最佳测定条件，检出限为0．02μg.mL^-1，回收率为96．5％－102．1％，RSD为1．65％－2．83％。该法准确、快速、简便，应用于水中磷的测定，结果令人满意。     

ICP-AES法直接测定中成药中的铅、镉、铜

采用ICP－AES法同时测定了中成药样品中的铅、镉、铜。加标回收率为94．2％－102．4％，10次测定的RSD（n＝10）小于4．2％。方法操作方便，分析速度快，结果准确。     

ICP-AES测定地表水中总砷

用ICP—AES测定地表水中总砷，检出限为：2．97μg/L，回收率在95％-105％之间，相对标准偏差为1.13％-2．24％，结果令人满意。     

微波消解、流动注射-氢化物发生原子荧光光谱法测定三七中硒含量

用微波消解、流动注射－氢化物发生原子荧光光谱法测定三七中硒，通过实验选择最优化的测定条件，方法的检出限为0．30μg.L^-1，相对标准偏差为1．2％，线性范围为0－100μg.L^-1，相关系数为0．9999，回收率为96．7％－100．7％。     

ICP-AES测定饮用水源中的Cu、Mn、Pb、Cd、Zn

用ICP－AES法同时测定饮用水源中的Cu、Mn、Pb、Cd、Zn等重金属元素，具有基体效应小、测量范围宽等优点。检出限为0．2－4．0μg/L，回收率为91．5％－103．9％，相对标准偏差为0．29％－1．5％，测定密码样与实际样品，结果令人满意。     

环丙沙星在胶束体系中的荧光特性研究及应用

研究了环丙沙星在胶束体系中的荧光性质，发现十二烷基硫基酸对环丙沙星有较强的增敏作用。据此建立了胶束增敏荧光光谱法测定痕量环丙沙星的新方法，经样品测定，其线性范围为0．033－0．60μg.mL^-1，检出限为0．033μg.mL^-1，回收率为94．0％－98．1％相对标准偏差为1．5％－2．8％。     

Undulations,steric interaction and cohesion of fluid membranes

Summary The theory of undulations of fluid membranes is reviewed and in some parts extended. The functional dependences of the steric interaction of undulating membranes are derived in a new way from simple physical arguments. Discussing the competition between steric repulsion and van der Waals attraction, one finds that membranes which usually separate (e.g. giant egg lecithin vesicles) should cohere if under lateral tension. The contours of two cohering vesicles observed when egg lecithin was swelling are analysed to show that the net energy of cohesion can be extremely small (≲10⁻⁵ erg cm⁻²). Paper presented at the ?Meeting on Lyotropics and Related Fields?, held in Rende, Cosenza, September 13–18, 1982.     

Surface-modified magnetic nanoparticles with lecithin for applications in biomedicine

Magnetic nanoparticles were prepared by thermal decomposition and adsorbed with lecithin by applying ultrasonication. The size and saturation magnetization changes of magnetic nanoparticles were observed with different lecithin concentration, and the maximum tolerated dose (MTD) and toxicity of magnetic fluid was investigated through a biological test. As the added lecithin concentration increased in a weight loss test by heating of magnetic particles, the thickness of lecithin-adsorption layer increased non-linearly, and the proper adsorption amount was observed in the lecithin concentration of 20% (w/v). The dispersibility and magnetic property of lecithin-adsorbed magnetic nanoparticles was the most excellent when the ultrasonic holding time was 1.5 h. Also, the maximum tolerated concentration with best cell viability was 32 μg/ml by in vitro test, and lecithin-adsorbed magnetic fluids showed the improved biocompatibility by 1.2 times compared with pure magnetite magnetic fluids.     

BLM成膜液中胆固醇与卵磷脂相互作用的光谱学研究

结合胆固醇与卵磷脂的拉曼光谱,分析了BLM成膜液中胆固醇与卵磷脂的相互作用。得出膜液中胆固醇与卵磷脂的最佳配比为1∶4。室温下,电化学实验的结果表明,以此种比例配置的膜液使膜的稳定性得到提高,导电率减小。     

Study of glucose oxidase–l-α-lecithin Langmuir film formation on air–water interface

The present paper describes the formation of glucose oxidase (GOx)–l-α-lecithin Langmuir film on air–water interface by spreading GOx solution directly onto subphase covered with layer of lecithin. The optimum experiment conditions were obtained according to the experimental results. Two phase transition processes were observed under surface pressure ranges of 8.0–11.0 mN/m and 15.0–30.0 mN/m, which represented the movement of GOx molecules under the lecithin layer and the reorientation of GOx molecules in the lecithin layer and/or expulsion of GOx molecules from the lecithin layer, respectively. The forces of GOx molecules that interacted with the lecithin layer were hydrogen bonding and hydrophobic force. An atomic force microscopy image of GOx–lecithin film deposited on Au (1 1 1) surface in optimal conditions gives evidence of well-ordered GOx molecules in the lecithin layer. As a target of this research, this work provides a new way to prepare biomimetic film and design glucose biosensors in future.     

Fluorescence anisotropy and light-scattering studies of the interaction of insulin with liposomes

The interaction between zinc-stabilized insulin and lecithin liposomal membranes was studied using DPH fluorescence anisotropy and light-scattering techniques. To ascertain a possible influence of a charge on the insulin molecule, experiments were performed at pH 4.5 (insulin possesses a positive charge) and at pH 7.4 (the charge of insulin is negative). Measurements at pH 4.5 revealed significant changes in scattered light intensity induced by the addition of insulin to lecithin liposomes. With increasing time of storage of liposomes the insulin effect became faster and more pronounced. At pH 7.4, significant changes in scattered light were registered only in the case of liposomes stored for 5 days. In these liposomes a peroxidation process of lecithin was revealed. No significant changes induced by insulin were observed in DPH fluorescence anisotropy either at pH 4.5 or at pH 7.4, which suggested the absence of an interaction of insulin with the hycrophobic core of liposomes. Thus, the observed changes in scattered light could be interpreted in terms of the insulin association to the liposomal surface in the case of phospholipid peroxidation and/or acidic pH.     

Determination of bakkenolide A in rat plasma using liquid chromatography/tandem mass spectrometry and its application to a pharmacokinetic study

A sensitive rapid analytical method was established and validated to determine the bakkenolide A (BA) in rat plasma. This method was further applied to assess the pharmacokinetics of BA in rats receiving a single dose of BA. Liquid chromatography tandem mass spectrometry in multiple reaction monitoring mode was used in the method, and costundide was used as internal standard. A simple protein precipitation based on methanol was employed. The combination of a simple sample cleanup and short chromatographic running time (2.4?min) increased the throughput of the method substantially. The method was validated over the range of 1-1000?ng/mL with a correlation coefficient?>?0.99. The lower limit of quantification was 1?ng/mL for BA in plasma. Intra- and inter-day accuracies for BA were 93-112% and 103-104%, respectively, and the inter-day precision was less than 15%. After a single oral dose of 20?mg/kg of BA, the mean peak plasma concentration (C(max) ) of BA was 234.7?±?161?ng/mL at 0.25?h. The area under the plasma concentration-time curve (AUC(0-24 h) ) was 535.8?±?223.7?h·ng/mL, and the elimination half-life (T(1/2) ) was 5.0?±?0.36?h. In case of intravenous administration of BA at a dosage of 2?mg/kg, the area under the plasma concentration-time curve (AUC(0-24 h) ) was 342?±?98 h?ng/mL, and the elimination half-life (T(1/2) ) was 5.8?±?0.7?h. Based on the results, the oral bioavailability of BA in rats at 20?mg/kg is 15.7%. Copyright ? 2012 John Wiley & Sons, Ltd.     

Sol-gel transition in worm-like micelles

Summary The statical and dynamical properties of lecithin/H₂O/cyclohexane cylindrical reverse micelles are investigated as a function of lecithin volume fraction, ϕ, and temperature at fixed water/lecithin ratio,w ₀. The viscosity data are well fitted by the Cates model when the breathing mode of micelles is taken into consideration, overlapping with the breaking and reforming mechanisms. We present some results from Brillouin-scattering experiment, performed across the sol-gel transition. In order to explain the experimentally observed ϕ-dependence of the hyperacoustic parameters, a mechanical model was developed from which the ϕ-dependence of the micelle size distribution was obtained. From a comparison with the viscosity data the entanglement length was estimated. Furthermore some new results from an incoherent quasi-elastic neutron scattering experiment are presented. The whole body of the experimental results suggests for a sol-gel transition triggered by topologic phenomena. When the lecithin volume fraction increases, the kinetic equilibrium between the breaking and reforming mechanisms of the micelles shifts the mean micelle length towards higher values and the entanglement of the micelles becomes highly favourable. The obtained results are discussed and compared with other findings in literature. Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994.     

Recording ion channels across soy-extracted lecithin bilayer generated by water-soluble quantum dots

We report on the quantum dot (QD)-induced ion channels across a soya-derived lecithin bilayer supported on a laser drilled of ~100 μm aperture of cellulose acetate substrate that separates two electrolytic chambers. Adequate current bursts were observed when the bilayer was subjected to a gating voltage. The voltage-dependent current fluctuation, across the bilayer, was attributed to the insertion of ~20?nm sized water-soluble CdSe QDs, forming nanopores due to their spontaneous aggregation. Apart from a closed state, the first observable conductance levels were found as 6.3 and 11?nS, as for the respective biasing voltages of ?10 and ?20?mV. The highest observable conductance states, at corresponding voltages were ~14.3 and 21.1?nS. Considering two simplified models, we predict that the non-spherical pores (d_nspore) can be a better approximation over spherical nanopores (d_spore) for exhibiting a definite conductance level. At times, even d_nspore?≤?4d_spore and that the non-spherical nanopores were associated with a smaller No. of QDs than the case for spherical nanopores, for a definite conductance state. It seems like the current events are partly stochastic, possibly due to thermal effects on the aggregated QDs that would form nanopores. The dwell time of the states was predicted in the range of 384–411?μs. The ion channel mechanism in natural phospholipid bilayers over artificial ones will provide a closer account to understand ion transport mechanism in live cells and signaling activity including labelling with fluorescent QDs.     

Development and Validation of a Spectrofluorimetric Method for the Determination of Erlotinib in Spiked Human Plasma

A rapid and sensitive spectrofluorimetric method was developed and validated for the determination of erlotinib (ETB), a potent anticancer drug, in spiked human plasma without any derivatization. The described method was validated and the analytical parameters of linearity, accuracy, precision (intra- and inter-day), limit of detection (LOD), and limit of quantification (LOQ) were evaluated. The relation between the fluorescence intensity and concentration was found to be linear (r² 0.9998) over the range 125 to 1000?ng/mL with the detection limit of 15?ng/mL. A simple liquid-liquid extraction method was followed in order to extract the drug from spiked plasma. The mean absolute recoveries of ETB were 85.59?% (±0.57), 86.91?% (±1.77) and 89.31?% (±3.01) at spiked plasma ETB concentration of 5000, 3750 and 2500?ng/mL, respectively. The spectrofluorimetric method presented here is a rapid, simple, specific, and reproducible method and can be used to characterize the plasma pharmacokinetics of ETB.     

A new ¹⁵N tracer method to determine N turnover and denitrification of Pseudomonas stutzeri

Although denitrification is one of the key processes of ecosystem N turnover, the understanding of the regulation of the denitrification pathway is still limited due to the lack of feasible methods for the quantification of N? formation. Based on the previously developed isotope pairing method, we present a new in vitro 1?N tracer method for the quantification of N? released from denitrification by bacterial cultures. The application of the new method was enabled by replacing the background air in the sample flasks with a gas mixture of He and O? with an approximately 50-fold reduced N? background (1.7% v/v), allowing for a direct and sensitive quantification of N? formation with isotope-ratio mass spectrometry after 1?N-labelling on the one hand, but leaving the method relatively insensitive to intrusion of ambient N? on the other hand. The method was tested on bacterial cultures of Pseudomonas stutzeri grown at different oxygen levels. Additionally, NO and N?O formation were determined with a chemoluminescence analyser and a gas chromatograph, respectively. Following labelling with 1?N-ammonium and 1?N-nitrate, it could be shown that P. stutzeri used ammonium preferably for biomass build-up, and nitrate preferably as electron acceptor. Between 84-107% of the total available N could be recovered. Due to the high sensitivity of the new method only low levels of 1?N tracer were necessary, minimising substrate-induced effects and making this method also an appropriate tool for the use on soil cores. By that it offers a new method for studying denitrification in terrestrial ecosystems.