柠檬酸色谱分离过程的吸附性质研究

 提出了一种通过在分析型柱上测定和模拟不同温度时的柱床空隙率和吸附等温线等热力学性能的变化行为 ,来筛选和研究用于从发酵液中以色谱法分离提纯柠檬酸的固定相结构的方法。     

Computer simulation as a tool for the rapid optimization of the high-performance liquid chromatographic separation of a tryptic digest of human growth hormone.

Computer simulation was used to optimize the separation of a tryptic digest of recombinant human growth hormone using reversed-phase high-performance liquid chromatography in a gradient mode. DryLab G/plus software modelled the retention behavior of the complex tryptic digest mixture as a function of gradient conditions, based on data from two experimental gradient runs. The theoretical optimum separation conditions were rapidly obtained and reproduced experimentally. Resolution did not simply increase as gradient steepness was decreased, rather, an intermediate gradient time provided maximum sample resolution. The simulation results also indicate that the method is reasonably rugged, with little change in the separation expected for different high-performance liquid chromatography systems, and changes in the separation can be compensated by a change in the gradient steepness. Computer simulation can also be useful to quickly reoptimize conditions for a new column, if it fails to provide the same separation.     

Separation method based on affinity reaction between magnetic and nonmagnetic particles for the analysis of particles and biomolecules

A separation method is reported for particle and biochemical analysis based on affinity interactions between particle surfaces under magnetic field. In this method, magnetic particles with immunoglobulin G (IgG) or streptavidin on the surface are flowed through a separation channel to form a deposition matrix for selectively capturing nonmagnetic analytes with protein A or biotin on the surface due to specific antigen (Ag)--antibody (Ab) interactions. This separation method was demonstrated using model reactions of IgG--protein A and streptavidin-biotin on particle surface. The features of this new separation method are (1) the deposited Ag-Ab complex can be examined and further analyzed under the microscope, (2) a kinetic study of complex binding is possible, and (3) the predeposited matrix can be formed selectively and changed easily. The detection limits were about 10(-11) g. The running time was less than 10 min. The selectivities of studied particles were 94% higher than those of label-controlled particles. This method extends the applications of analytical magnetapheresis to nonmagnetic particles. Preliminary study shows that this separation method has a great potential to provide a simple, fast, and selective analysis for particles, blood cells, and immunoassay related applications.     

Computer-assisted transposition of conditions in high-performance thin-layer chromatography to high-performance liquid chromatography for the separation of pesticides

Summary A computer-assisted method is presented for mobile phase selection for the optimal separation of pesticides by HPTLC and HPLC. The system is based on a plot of solute retention value and separation criterion vs. binary mobile phase composition for graphic optimization. The result of HPTLC can be transposed to HPLC for optimal separation. The transposition equation is given.     

Some theoretical aspects of the use of isotopic exchange in a heterogeneous liquid system for radiochemical separations

Theoretical possibilities of the application of isotopic exchange in a heterogeneous liquid system to the separation of radionuclides have been investigated. With certain simplifying assumptions, equations were derived which enable the calculation of both the separation efficiency and volume concentration for a one-stage separation process under static or dynamic conditions. The relations obtained can be used in the choice of an appropriate method for the separation and simultaneous enrichment of trace amounts of radionuclides from large-volume liquid samples by equilibrium isotopic exchange.     

可调移动重叠分离图法用于高效液相色谱多台阶梯度分离条件优化的研究

计算机辅助高效液相色谱（HPLC）分离条件优化可以低成本、快速地得到优化的分离条,因而已较为广泛地用于复杂样品的分离分析。基于移动重叠分离图方法,又发展了一种新型的多台阶梯度分离条件的优化方法可调移动重叠分离图法。该方法通过预测不同流动相条件下各组分的保留时间、峰宽和分离度,绘制出对于样品中各组分的重叠分离区域图。在对当前台阶流动相组成进行优化的同时,考虑其对后面一到两个台阶上流出组分保留的影响,实时地重新绘制对于后面台阶上流出组分的重叠分离区域图。通过观察当前台阶流动相条件对当前台阶和后面台阶上流出组分分离的影响,综合考虑样品中所有组分的分离情况,找到更接近全局最优的分离条件。通过扫描的方法对优化得到的分离条件进行微调,能够进一步提高分离效果。采用文献数据对可调移动重叠分离图法的应用加以说明,在二元流动相体系下,证明了该方法在HPLC方法建立方面的优越性。     

Application of isotopic exchange for the determination of tin in nickel

A method for the determination of tin in nickel by activation analysis is described. Isotopic exchange is used for the separation of tin from nickel. The most favourable conditions for the separation have been determined, under which more than 99 % of the tin can be recovered in 7-8 min.     

A Semi-Automated Technique for the Separation and Determination of Barium and Strontium in Surface Waters by Ion Exchange Chromatography and Atomic Emission Spectrometry

Abstract

A semi-automated method for the separation and the analysis of barium and strontium in surface waters by atomic emission spectrometry is described. The method employs a semi-automated separation technique using ion exchange and an automated aspiration-analysis procedure. Forty specimens can be prepared in approximately 90 minutes and can be analyzed for barium and strontium content in 20 minutes. The detection limits and sensitivities provided by the described technique are 0. 00 3 mg/l and 0.01 mg/l respectively for barium and 0.00045 mg/l and 0.003 mg/l respectively for strontium.     

Continuous separation of particles using a microfluidic device equipped with flow rate control valves

We propose herein an improved microfluidic system for continuous and precise particle separation. We have previously proposed a method for particle separation called "pinched flow fractionation." Using the previously reported method, particles can be continuously separated according to differences in their diameters, simply by introducing liquid flows with and without particles into a specific microchannel structure. In this study, we incorporated PDMS membrane microvalves for flow rate control into the microfluidic device to improve the separation accuracy. By adjusting the flow rates distributed to each outlet, target particles could be precisely collected from the desired outlet. We succeeded in separating micron and submicron-size polymer particles. This method can be used widely for continuous and precise separation of various kinds of particles, and can function as an important part of microfluidic systems.     

Activation of Cellulose Assisted by CO2 for the Preparation of a Superhydrophobic Nanocoating

There is increasing demand for superhydrophobic materials, which can be used for separating oil and water efficiently. To avoid secondary pollution, it is desirable to prepare such materials with green technology. Here, we present an environmentally benign method for fabricating superhydrophobic materials by using organic base based solvents in which cellulose can be dissolved and activated. The dissolved cellulose could be chemically modified with a silanization reagent, and the solvent could be recycled after CO₂ was removed. The obtained cellulose nanocoating exhibited excellent hydrophobic effects. By spraying it on filter paper (water contact angle (WCA)=165°) for oil and water separation, the separation efficiency of more than 95 % was achieved; ultrasonication of an ordinary sponge in its dispersion (WCA=163°), meant it could be used as an oil absorber. It can also absorb a certain amount of bisphenol A (BPA), with the concentration decreasing by 66 % from the original concentration (0.1 mm ). Besides the high separation efficiency, it is resistant to a wide range of pH solutions, which means that it could be used in harsh environments. More importantly, the process is cost‐effective, the solvent can be recycled, and the whole process is green. Thus, the activation method provides a green route for the preparation of other cellulose‐based materials.     

Size separation of proteins by capillary zone electrophoresis with cationic hitchhiking

The paper describes a method of size separation of proteins by capillary sieving electrophoresis with cationic surfactant. Proteins are separated within 12 min with repeatability of migration times better than 0.2%. Some proteins achieve the separation efficiency of 200,000 theoretical plates. The method can be used for determination of protein relative molecular masses. The accuracy of the determined relative molecular masses and the limitation of the method were investigated by the analysis of more than 60 proteins. The method also allows separation of protein oligomers. Proteins can be quantitated after the electrokinetic injection in the concentration range 0.07-0.43?g/L. The average detection limit is about 2?mg/L.     

Comparison of comprehensive two-dimensional gas chromatography and gas chromatography--mass spectrometry for the characterization of complex hydrocarbon mixtures

In this paper, we compare the current separation power of comprehensive two-dimensional gas chromatography (GCxGC) with the potential separation power of GC-mass spectrometry (GC-MS) systems. Using simulated data, we may envisage a GC-MS contour plot, that can be compared with a GCxGC chromatogram. Real examples are used to demonstrate the current potential of the two techniques in the field of hydrocarbon analysis. As a separation technique for complex hydrocarbon mixtures, GCxGC is currently about as powerful as GC-MS is potentially powerful. GC-MS has not reached its potential separation power in this area, because a universal, soft ionization method does not exist. The greatest advantage of GCxGC is, however, its potential for quantitative analysis. Because flame-ionisation detection can be used, quantitative analysis by GCxGC is much more robust, reliable and reproducible.     

Selectivity differences for C18 and C8 reversed-phase columns as a function of temperature and gradient steepness. II. Minimizing column reproducibility problems

The choice of T and tG as variables for controlling selectivity and resolution during reversed-phase liquid chromatography (RPLC) method development can be used to minimize problems caused by column batch-to-batch irreproducibility. When a new column fails to provide adequate separation of the sample, altered values of T and tG can be predicted that will restore the separation obtained with the previous column. Alternatively, columns from different manufacturers can be tested during method development, in order to find a common set of conditions (T and tG) that provide acceptable separation with two or more of these columns. In this way, any of several columns from different sources become usable for the method. Examples are shown of these different computer-assisted procedures for minimizing problems due to column variability.     

反相高效液相色谱中复杂体系二元多台阶梯度分离条件快速优化方法

提出了一种反相高效液相色谱中二元多台阶梯度分离条件快速优化方法。通过数次线性梯度初始实验，求得溶质的保留方程。在此基础上，利用重叠分离区域图（OSRM）方法，快速求得复杂样品的最佳多台阶梯度分离条件。该方法只需要几个小时就可以完成对复杂样品分离条件的优化，并通过对中药川芎提取物的分离加以验证，获得了较好的预测精度和分离效果。     

An on-column derivatization method for the determination of the enantiomeric excess of chiral primary amines via indirect enantioseparation by micellar electrokinetic chromatography

A method used for determining the enantiomeric excess (ee) value of chiral amino compounds by MEKC is described. In this method, the plug-plug type electrophoretic medicated microanalysis technique was employed to convert the enantiomers of chiral amino compounds into their diastereomers through an on-column derivatization with o-phthaldialdehyde and the chiral reagent N-acetyl-L-cysteine. Afterwards, the resulting diastereomers were easily separated with a nonchiral MEKC approach. The on-column derivatization conditions and the separation conditions were optimized and the method was validated with five chiral amino compounds. The present method can be used for assaying the ee value of chiral amino compound with various structural features, especially for those that have no UV chromophore. Therefore, the method can be potentially used for screening or evaluation of the asymmetric catalysts developed by the combinatorial chemistry. In this case, the ee values of chiral products with various structures need to be measured; however, this is difficult for direct chiral separation approach due to the fact that the chiral selectivity is strongly dependent on the structure of the analytes. The method is simple, reliable, and automatic.     

Separation of germanium from some elements by adsorption on silica gel

In the search for an efficient method of recovery of germanium from concentrated mineral acid solutions, silica gel has been found to be a selective adsorbent for this element. A method of quantitative separation of gallium from germanium is described which can be applied for the preparation of⁶⁸Ge−⁶⁸Ga isotope generator and for the isolation of⁶⁸Ge from a zinc target. The applicability of the present method was also studied for the separation of a gertarget. The applicability of the present method was also studied for the separation of a germanium matrix in determining admixtures in semiconductor germanium samples by activation analysis.     

Development of overlapping repeated separation of steviol glycosides with counter current chromatography and a comparison with a conventional repeated separation method

Repeated separation is a valuable method in counter current chromatography, especially on a preparative scale. It can greatly reduce the separation time and the consumption of solvent. In this study, an overlapping repeated separation method was developed. Meanwhile, this method was used to separate steviol glycosides and compared with conventional repeated separation method. The results show that both methods are effective ways for countercurrent chromatography to prepare compounds but the overlapping repeated separation method requires fewer time and solvent than the conventional repeated separation method. So this novel repeated separation method has enormous potential for a preparative separation of target compounds and is very useful for the high‐throughput purification of natural products.     

Treatment of soy bean process water using hybrid processes

The soy bean process water that is a by-product of soy processing technology can be utilized with a hybrid separation system recommended and investigated in this work. The aims of the soy bean water processing are to i.) concentrate the valuable components of the soy process water and ii.) reuse its water content. Two hybrid separation systems are considered and investigated: ultrafiltration followed by nanofiltration and centrifugal separation followed by nanofiltration. These hybrid separation systems are new in the area of their current application. Experiments verify that centrifugal separation is a more appropriate pre-treatment method for the removal of suspended solids and for the preservation of the sucrose content of the soy bean process water than ultrafiltration. Total sucrose can be rejected by nanofiltration membrane forming a sugar-rich retentate that contains other valuable components, too. Both tested hybrid processes result in clear and reusable permeates with low chemical oxygen demand that can be recycled to the production process reducing its water consumption and improving its sustainability. The recommended new hybrid separation system, centrifugal separation followed by nanofiltration, proves to be successful in this area of the biochemical industry.     

Separation of gallium, indium and thallium by extraction with n-octylaniline in chloroform

Extraction of gallium(III), indium(III) and thallium(III) with n-octylaniline in chloroform at various concentrations of hydrogen halide acids (HCl, HBr, HI) has been studied and a scheme for their separation proposed. The procedure can be successfully applied to the separation and determination of gallium in presence of mercury, bismuth, manganese, zinc and lead; indium in presence of bismuth, antimony, lead, mercury, cadmium and zinc; and thallium in presence of mercury, cadmium, manganese, aluminium, tin and antimony. The advantage of the method is that the reagent can be recovered for reuse. The method is simple, rapid, and effects clear-cut separation.