固相微萃取活性炭涂层萃取头的制备及其对卤代烃化合物的萃取

利用自制的有机硅树脂胶粘剂和粉状活性炭制成活性炭涂层萃取头。该萃取头富集能力强,对氯仿、四氯化碳、三氯乙烯、四氯乙烯4种卤代烃化合物的富集率达到13.8~18.7倍;热稳定性好,最高使用温度可达290 ℃;使用寿命长,250 ℃解吸条件下可反复使用140次以上。上述4种化物固相微萃取-气相色谱分析的结果表明,方法的最低检出质量浓度为0.008~0.05 μg/L。采用该萃取头对含有该4种卤代烃化合物的实际水样进行了SPME-GC分析,4种化合物的回收率为95.5%~104.6%。     

双水相萃取体系的研究

有机溶剂;分相机理;双水相萃取体系的研究     

苯甲酸稀溶液的萃取特性

磷酸三丁酯;正辛醇;苯甲酸稀溶液的萃取特性     

胺类萃取剂

高级脂肪胺(又称为长碳链脂肪胺)一般指碳链超过十二个碳的脂肪胺而言。就胺的类型来分,又有伯、仲、叔胺及季铵盐四种,它们在国民经济中的许多部门应用广泛。例如,长碳链脂肪胺用作钛、铍、钾盐及其他矿物的浮选剂;在农业上作为钾肥的抗结块剂、农药的     

丁醇稀溶液的络合萃取

有机酸;烷基膦酸酯;丁醇稀溶液的络合萃取     

固相微萃取研究进展

<正>固相微萃取(solid-phase microextraction,SPME)是20世纪80年代末发展起来的一种新型样品前处理方法,最先由Waterloo大学的Pawliszyn等提出。固相微萃取技术的发展主要体现在新型涂层材料的出现及其在环境、食品、生物等领域应用的不断深入两个方面。     

丁醇稀溶液的络合萃取

有机酸;烷基膦酸酯;丁醇稀溶液的络合萃取     

双酚A分子印迹聚合物为萃取介质搅拌饼固相萃取的制备及其萃取性能研究

以双酚A为模板,4-乙烯基吡啶为单体,利用整体材料"原位"聚合技术制备分子印迹聚合物为基质的萃取饼,并与利用一次性注射器空管加工而成的萃取器相结合,建立了分子印迹搅拌饼固相萃取(MIP-SCSE)技术。考察了制备条件对MIP-SCSE选择吸附性能的影响。在此基础上,与高效液相色谱-二极管阵列检测器联用,探讨MIP-SCSE对环境水样中双酚A及其它酚类物质的选择萃取性能,考察萃取过程中基底离子强度、pH值以及吸附与解吸时间等萃取条件对萃取性能的影响。结果表明;在最佳萃取条件下,MIP-SCSE对模板分子及其它酚类物质具有一定选择性能和较高的富集能力,对双酚A的线性范围为1.0～200μg/L;检出限LOD(S/N=3)为0.67μg/L;定量限LOQ(S/N=10)为2.24μg/L。在实际水样分析中,模板分子加标回收率为86.2%～112.2%。在MIP-SCSE使用过程中,萃取饼不与容器壁接触,因此具有优良的使用寿命,至少可连续使用600 h。     

萃取光度法测定诺氟沙星

诺氟沙星(NFXC)与溴甲酚绿(BCG)在pH3.2的邻苯二甲酸氢钾缓冲溶液中形成可被萃取到氯仿相的离子缔合物,在420nm最大吸收峰处测定离子缔合物的吸光度。线性范围为0-18mg·L-1,此法用于诺氟沙星滴眼液和诺氟沙星胶囊中诺氟沙星含量的测定,结果满意。     

对氨基酚络合萃取机理的探讨

对氨基酚络合萃取机理的探讨;对氨基酚; 络合萃取; 萃取机理; 萃取反应热     

Preparation of Functional Fluorescent Microspheres Used for HTS and Their Interaction with Biomolecules

There is considerable interest in protein adsorption onto microspheres because of its importance in a wide range of biomedical applications, such as artificial tissues and organs, drug delivery systems, biosensors, solid-phase immunoassays, immunomagnetic cell separation and immobilized enzymes or catalyst. It has been well known that the interaction between proteins and microspheres plays important roles in this process. Major interaction involved in the adsorption can be classified as electrostatic, hydrophobic and hydrogen-bonding. Indeed, adsorption of proteins onto microspheres is a complex process and often can involve many dynamic steps, from the initial attachment of the protein on the surface of microspheres to the equilibrium. Also the conformation of proteins probably occurs to a certain degree of deformation or structural change due to the large area of contact. Recently, much interest has been shown in sulfonated microspheres, since sulfonate-group itself is one of components in bio-bodies, as well as is sensitive to the change of pH or ionic strength. Indeed, so far, scanty investigations have been performed in the full range. Also few researches have involved the data on adsorption rate and the maximum amount of protein adsorbed, or the reversibility of the process and conformational change of protein adsorbed as well.In present study, BSA (bovine serum albumin) was chosen as the model protein and sulfonated PMMA [poly(methyl methacrylate)] microspheres as the matrix to investigate the adsorption process.The purpose is to show some information especially the intrinsic information involved by the adsorption process Adsorption of BSA onto sulfonated microspheres (MS) has been investigated as a function of time, protein concentration and pH. The adsorption appears to be a reversible process and the presence of sulfonate groups can play important roles in the adsorption process, so as to increase the amount of protein adsorbed and influences the interaction of BSA molecules. Fig. 1 also shows that the reciprocation between unadsorbed and adsorbed BSA or rearrangement of adsorbed BSA molecules does not produce visible change in the properties of the adsorbed protein. Close to the isoelectric point of BSA (pI 4.7), the amount of protein adsorbed exhibits a maximum. A higher or lower pH results in the significant decrease of the adsorption amount. This is related to the dependence of BSA conformations at different pH conditions.     

Polysaccharide-modified iron oxide nanoparticles as an effective magnetic affinity adsorbent for bovine serum albumin

The magnetic separation technique based on magnetic iron oxide nanoparticles (MNPs) has potential applications in protein adsorption and purification, enzyme immobilization, cell sorting, nucleic acid detachment, and drug release. However, the naked MNPs are often insufficient for their hydrophilicity, colloidal stability, and further functionalization. To overcome these limitations, chitosan was firstly carboxymethylated and then covalently conjugated on the surface of the MNPs ranging in size from about 5 to 15 nm, which were prepared by co-precipitating iron (II) and iron (III) in alkaline solution and then treating under hydrothermal conditions. It was found that such modification did not result in the phase change of the MNPs, and the resultant modified nanoparticles were still superparamagnetic. In particular, the colloidal stability of MNPs in aqueous suspension was improved after the surface modification. By investigating the adsorption of bovine serum albumin (BSA) on the modified MNPs, it was observed that the adsorption capacity of the BSA on the modified MNPs increased rapidly within several minutes and then reached the maximum value at about 10 min. The adsorption equilibrium isotherm could be fitted well by the Langmuir model. The medium pH affected greatly the adsorption of the BSA. The maximum adsorption of the BSA occurred at the pH value close to the isoelectric point of the BSA, with a saturation adsorption amount of 94.45 mg/g (25 °C). For the BSA feed concentration of 1.017 mg/ml, a high desorption percentage of 91.5% could be achieved under an alkaline condition (pH 9.4).     

SURFACE MODIFICATION OF MICROPOROUS POLYPROPYLENE MEMBRANES BY GRAFT POLYMERIZATION OF N,N-DIMETHYLAMINOETHYL METHACRYLATE

Surface modification of microporous polypropylene hollow fiber membranes was performed by radical-induced graft polymerization of N,N-dimethylaminoethyl methacrylate (DMAEMA). The influences of temperature, monomer concentration and pre-adsorbed amount of benzoyl peroxide on grafting degree were studied respectively. It was found that the appropriate graft temperature was 75℃, at which the grafting degree was the highest and the hydrolytic decomposition of DMAEMA the lowest. Scanning electron photomicrography and the average pore diameters of the modified membranes demonstrated that part of the micropores on the membrane surface was plugged by the grafted polyDMAEMA chains, especially at high grafting degree. Contact angle and water swelling experiments showed that a moderate grafting degree could improve the hydrophilicity of the membranes. In the range of I 1.3%o-12.0% grafting degree, the water swelling percentage reached its maximum (51.1%) and the contact angle reached its minimum (74 degrees). The bovine serum albumin (BSA) adsorption experiment indicated that the grafted polyDMAEMA had a dual effect on protein adsorption. At the first stage, the BSA adsorption decreased with increasing of DMAEMA grafting degree. As the interaction between BSA and polyDMAEMA on membrane surface increased, the BSA adsorption increased with increasing of DMAEMA grafting degree.     

Separation of serum proteins with uncoupled microsphere particles in a stirred cell

Submicron microspheres were used directly without ligand coupling for the batch and continuous separations of proteins. In the batch experiments for separating BSA (bovine serum albumin) from BHb (bovine hemoglobin), introducing both hydrophobic effects for BSA and electrostatic repulsion for BHb (and vice versa) was required for high selectivity, and microspheres with low number density of surface groups were advantageous. For the continuous experiments, the utilization of a stirred cell was successful, where the microspheres were in the form of latex with good dispersion of particles. The flow rate without a pump was 0.5–1.3 ml min⁻¹, and the ratio of BSA and BHb was varied. In the experiments for eliminating BHb from BSA, elution curves of BHb corresponded to the single component breakthrough curves, while those for BSA did not. The latter is believed to be due to the interference by BHb in the adsorption of BSA.     

Electrostatic interaction between chitosan-modified latex particles and bovine serum albumin

Electrostatic interaction between poly(methyl methacrylate) latex particles with different levels of chitosan modification and bovine serum albumin (BSA) was investigated. The critical flocculation concentration is in the range 5–15 nmol dm⁻³ for these latex products toward added BSA. A series of isothermal equilibrium adsorption experiments shows that the adsorption process is divided into two distinct intervals. Adsorption of BSA on latex particles in intervals I and II is primarily controlled by charge neutralization and hydrophobic interaction, respectively. Intervals I and II can be reasonably described by an empirical parabola equation and the Langmuir isotherm model, respectively. The maximum amount of BSA adsorbed per unit weight of polymer particles was observed at pH ≅ 5. A maximum elution yield of about 80% can be achieved using NaSCN as the elution electrolyte, and NaSCN is more effective in inducing desorption of BSA from the particle surface than NaCl. The chitosan content has very little effect on the interaction between latex particles and BSA. By contrast, the influence of the content of 2,2′-azobis(2-amidinopropane) dihydrochloride, a cationic initiator used in preparing the chitosan-modified latex products, on the BSA adsorption process is significant. Received: 26 March 1999 Accepted in revised form: 3 June 1999     

壳聚糖亲和磁性毫微粒的制备及其对蛋白质的吸附性能研究

以壳聚糖为包裹材料包埋自制的磁流体 ,制备了具有核 壳结构的磁性毫微粒 ,并偶联色素配基CibacronBlue 3GA(偶联量 1 4 .5μmol/mL)得到了一种新型亲和磁性毫微粒 .结果表明 ,所得亲和磁性微球具有较窄的粒径分布、形状规整 .以牛血清白蛋白 (BSA)和溶菌酶 (Lys)为目标蛋白 ,考察了该亲和磁性毫微粒的吸附性能 ,发现其对BSA和Lys的吸附量分别为 4和 2 8mg/g,吸附行为满足Langmuir吸附等温式 ,且对时间依赖性小而对溶液离子强度敏感 .     

Modeling of the whole expanded-bed protein adsorption process with yeast cell suspensions as feedstock

Expanded bed adsorption of bovine serum albumin (BSA) directly from a feedstock containing whole yeast cells has been investigated with an anion-exchanger DEAE Spherodex M. In the presence of 6% (w/w) yeast cells, the axial liquid-phase dispersion coefficient was found in the order of 10(-6) m2/s, which felled into the common range of 1.0 x 10(-6)-1.0 x 10(-5) m2/s observed previously without the use of cell suspensions as mobile phase. We found that the static and dynamic binding capacity of BSA decreased with increasing the yeast cell concentration due to the competitive adsorption of cells onto the outer surface of the anion-exchanger. However, because of the small size of the adsorbent, the large pore diffusivity of protein and the favorable column efficiency (low axial dispersion coefficient), the dynamic binding capacity of BSA in the presence of 6% (w/w) cells in the expanded bed reached 86% that of the equilibrium adsorption density. Then, the whole expanded bed adsorption process of BSA in the presence of cells, including feedstock loading, washing and elution steps, was predicted using a mathematical model with parameters all determined independently. In the elution stage, the steric mass-action adsorption isotherm with salt concentration as one of the model parameters was used to predict the step-gradient elution process with salt concentration increases. Computer simulations showed that the model was in good agreement with the experimental results for the whole operation process.     

Effect of surface charge on adsorption of bovine serum albumin 2. Interaction of protein molecules with an anionic monolayer,as studied by ellipsometry,radiotracer and surface tension measurements

The adsorption of bovine serum albumin (BSA) onto an anionic monolayer of sodium docosylsulfate (SDocS) spread at the air/water interface was studied by ellipsometry. The adsorption behavior of BSA was estimated from the observed changes in phase differences and in the ratio of reflection coefficients. The dynamic process of BSA adsorption was measured after the injection of BSA solution into the aqueous substrate of SDocS monolayer. The gentle stirring of the substrate solution for 10 min was found to be enough to make the solution homogeneous without damaging the monolayer. The adsorption characteristics of BSA onto a negatively charged surface was compared with that onto a positively charged surface previously reported.The amount of adsorption depended on time and showed a maximum with an initial rapid rise, followed by gradual decrease toward the ultimate equilibrium value. The amount and time of the maximum adsorption depended on the concentration of BSA added to the aqueous substrate.Separate radiotracer measurement, using³⁵S-labeled SDocS monolayer, which is insoluble by itself, revealed that SDocS is solubilized into the bulk solution when BSA is added to the aqueous substrate.     

RAFT of sulfobetaine for modifying poly(glycidyl methacrylate) microspheres to reduce nonspecific protein adsorption

The minimization of nonspecific protein adsorption is a crucial step in the development of bioseparation processes, immunoassays, and affinity diagnostics. Among the numerous biomaterials, polyzwitterions are known to effectively suppress protein and cell adhesion. This article describes the formation of monodisperse polymer microspheres coated with polysulfobetaine with the aim to limit nonspecific adsorption of bovine serum albumin (BSA) as a model protein. In this process, 2‐μm poly(glycidyl methacrylate) (PGMA) microspheres were prepared by dispersion polymerization. To render the microspheres hydrophilic and biocompatible, [3‐(methacryloylamino)propyl]dimethyl(3‐sulfopropyl)ammonium hydroxide (MPDSAH) was grafted from the surface by reversible addition‐fragmentation chain transfer (RAFT) polymerization. Elemental analysis of the modified microspheres revealed up to 20 wt % of poly{[3‐(methacryloylamino)propyl]dimethyl(3‐sulfopropyl)ammonimum hydroxide} (PMPDSAH). The microspheres were characterized in terms of particle size, morphology, and zeta potential. The amount of BSA nonspecifically adsorbed on the PMPDSAH‐modified microspheres decreased to half of that captured on the unmodified PGMA microspheres. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2273–2284     

4-(1H-imidazol-1-yl) aniline: A new ligand of mixed-mode chromatography for antibody purification

4-(1H-imidazol-1-yl) aniline (AN) was immobilized on Sepharose CL-6B (AN-Sepharose) for use as a new ligand of mixed-mode chromatography. Adsorption equilibria of immunoglobulin G (IgG) and bovine serum albumin (BSA) to AN-Sepharose were studied at extensive pH values (4.0–8.8) and salt concentrations (0–1.0 mol/L). Static binding studies indicated that AN-Sepharose had a good salt-tolerance property for IgG adsorption up to 1.0 mol/L NaCl. This was attributed to the combined ligand–protein interactions (hydrophobic interaction, hydrogen bonding and charge transfer interaction). By contrast with BSA, AN-Sepharose showed a high binding selectivity for IgG at NaCl > 0.2 mol/L. Dynamic binding capacities (DBC) of IgG and BSA at 10% breakthrough were measured at pH 4.0–8.8 by frontal analysis chromatography. IgG had DBC values over 40 mg/mL at pH 7.0–8.8, and the maximum reached 59 mg/mL at pH 8.0. At pH 5.0, a distinct drop in DBC to 8.5 mg/mL was observed, but that for BSA kept over 22 mg/mL. The result suggested that IgG could be selectively desorbed from AN-Sepharose by decreasing pH to about 5. Therefore, compared to BSA, AN-Sepharose exhibited a dual-selectivity for IgG in both adsorption and elution. Purification of IgG from bovine serum also confirmed the dual-selectivity. IgG purity of the pooled fractions by elution at pH 4.0, 4.5 and 5.0 reached 55% and the highest purity, 80%, was obtained at pH 4.5. The average purification factor of IgG was over 25. The results indicate that AN is a promising ligand of mixed-mode chromatography for antibody purification from a complex feedstock.