用最优化方法选择磺胺类药物的薄层色谱溶剂系统

薄层色谱是药学工作者最常用的分离分析手段,而溶剂系统的选择则是薄层色谱中最重要的问题。但目前在此问题上,人们往往只凭借经验而无比较实用的系统化方法可循,若实验者的经验较少,则会在溶剂系统选择上浪费大量时间或选出的溶剂系统不够合理。因此,笔者等曾提出一种比较实用的系统化方法:即利用均匀设计试验法选择溶剂系统组分,再利用单纯形优化法选择溶剂系统配比。本文通过对磺胺类药物的成功分离,进一步验证了该方法的可行性。     

“改进的棱柱形”优化系统在高效液相色谱中的建立和应用 Ⅰ.“棱柱形”溶剂强度优化系统的改进

本文建立了适于高效液相色谱的“Improved-PRISMA”优化系统,利用全范田二元线性梯度淋洗进行溶剂强度的优化,只需一次实验即可得知所需溶剂的最佳强度,简化了原“PRISMA”系统选择溶剂强度的过程。将此系统用于七个有机磷化合物的分离,得到了满意的结果。     

计算机辅助高效液相色谱梯度洗脱的优化

本文介绍了计算机辅助反相高效液相色谱梯度洗脱优化分离的方法。首先采用混合设计法，通过９个预试验建立目标函数，然后运用双因素（初始流动相组成Ｃ和梯度时间Ｔ）扫描技术，由计算机给出优化分离条件，实验结果和预示完全一致。     

薄层色谱溶剂系统的最优化方法的研究第Ⅷ报外部惩罚函数法

以１０种已知磺胺的混合物为例，采用外部惩罚函数法在计算机上处理数据，对其薄层色谱溶剂系统进行优化，优化的结果为甲苯：无水乙醇；１，２－二氯乙烷：三氯甲烷＝０．６８：０．７８：４．１３：４．４１，分离结果比较满意，是一种比较有效的系统化方法。     

常用溶剂的Fuzzy聚类分析

本文报道了应用Fuzzy聚类分析方法,以计算机为工具,对常用的81种溶剂按选择性的五个参数进行分类。分类结果较L.R.Snyder等人的分类有较大的改进。同时,本文还优选出21种色谱分析常用溶剂。 一、问题的提出 色谱工作者经常遇到溶剂选择问题,如溶剂萃取,液相色谱流动相的选择等。若事先知道常用溶剂的分类情况,则有可能从众多的溶剂中选择出性能较好、价格较低或毒性较小的溶剂,以满足实际工作的需要。     

薄层色谱溶剂系统的最优化方法的研究第Ⅷ报外部惩罚函数法

 以１０种已知磺胺的混合物为例，采用外部惩罚函数法在计算机上处理数据，对其薄层色谱溶剂系统进行优化，优化的结果为甲苯：无水乙醇；１，２－二氯乙烷：三氯甲烷＝０．６８：０．７８：４．１３：４．４１，分离结果比较满意，是一种比较有效的系统化方法。     

薄层色谱溶剂系统的优化设计

采用复合形法,根据色谱优化函数对肾上腺皮质激素类、磺胺类药物及银杏粉针剂的薄层溶剂系统进行了最优化设计。肾上腺皮质激素类药物的最佳溶剂系统为１,２－二氯乙烷－苯－甲醇（４．８１４．４２０．７８）;磺胺类药物的最佳溶剂系统为甲苯－无水乙醇－二氯乙烷－氯仿（２．３０１．４６３．３２２．９２）;银杏粉针剂的最佳溶剂系统为氯仿－甲醇－乙酸乙酯（３．３０３．２９３．４１）,实验结果与计算结果一致。     

用网格搜索寻优法选择分离6种青霉素类药物的薄层色谱溶剂系统

用网格搜索寻优法确定了分离６种青霉素类药物的薄层色谱溶剂系统。采用均匀设计法安排初始实验，借助计算机进行网格搜索寻优计算，在硅胶ＧＦ（２５４）板上成功地分离了青霉素钠、苯唑青霉素钠、磺苄青霉素钠、氨苄青霉素钠、氧哌嗪青霉素钠和羧苄青霉素钠，方法简便、有效。     

用网格搜索寻优法选择分离6种青霉素类药物的薄层色谱溶剂系统

 用网格搜索寻优法确定了分离６种青霉素类药物的薄层色谱溶剂系统。采用均匀设计法安排初始实验，借助计算机进行网格搜索寻优计算，在硅胶ＧＦ（２５４）板上成功地分离了青霉素钠、苯唑青霉素钠、磺苄青霉素钠、氨苄青霉素钠、氧哌嗪青霉素钠和羧苄青霉素钠，方法简便、有效。     

烟草中有机氯类农药多残留分析前处理方法对比研究

以烟草中有机氯类农药为研究对象,从检出限、回收率、重复性和色谱图4个方面系统比较了机械振荡萃取法、超声波溶剂萃取法、微波辅助萃取法和加速溶剂萃取法4种常用前处理方法。由于加速溶剂萃取法是在高温高压下进行萃取,在提取出残留农药的同时,也提取出更多的干扰物。机械振荡法、超声波溶剂萃取法和微波辅助萃取法各项结果差别较小,其中机械振荡萃取法回收率和重复性最好,但提取时间较长。考虑溶剂消耗和提取时间等方面的因素,微波辅助萃取是较理想的样品前处理方法。     

Calculation for liquid-liquid equilibria of quaternary alkane-ethyl acetate-methanol-water systems used in counter-current chromatography

The calculation of liquid-liquid equilibrium compositions of solvent systems is very important for the work on counter-current chromatography (CCC), especially the phase composition and volume ratio obtained from liquid-liquid equilibrium calculation. In this work, liquid-liquid equilibria of quaternary Arizona solvent systems, alkane-ethyl acetate-methanol-water, and related ternary systems are correlated and predicted using the non-random two-liquid model (NRTL). Hexane, heptane and isooctane are the used alkanes. The parameters in the model are regressed only with the special systems considered. Detailed comparison with experimental data shows that liquid-liquid equilibria of these systems can be predicted with greatly improved accuracy as compared to the group contribution method (UNIFAC).     

Optimized Ultrasonic Extraction for the Determination of Polyaromatic Hydrocarbons by Gas Chromatography–Mass Spectrometry

The presence of polycyclic aromatic hydrocarbons (PAHs) in soil is an issue of concern due to their harmful effects on human health. The goal of this study was to optimize ultrasonic extraction to establish an efficient, easy, and low-cost method for the determination of 16 priority PAHs in soil. The time of extraction and solvent systems were optimized with the analysis by gas chromatography–mass spectrometry. The method was validated, and the optimum results were obtained using 1:1 cyclohexane:acetone and 1:1 hexane:acetone solvent systems with 30- and 60-min sonication times.     

Quick method for separating target compounds from the bark of Maqian (Zanthoxylum myriacanthum var. pubescens) by high‐performance countercurrent chromatography

Choosing a suitable solvent system for a countercurrent chromatography separation presents a challenge for many researchers. In this study, we introduce a quick method of separating a target compound from the bark of Zanthoxylum myriacanthum var. pubescens by countercurrent chromatography. This method relies on the thin‐layer chromatography based generally useful estimation of solvent systems. This paper will present how to quickly choose a suitable solvent system with a thin‐layer chromatography based generally useful estimation of solvent systems working chart. O‐Methyltembamide ( 1 ) was enriched by countercurrent chromatography using n‐hexane/ethyl acetate/methanol/water (6:4:6:4) as the solvent system. Further purification was achieved by high‐performance liquid chromatography with purities of 98.2% from Z. myriacanthum var. pubescens bark.     

Solvents showing the external heavy atom effect in phosphorimetry

Ten solvents containing heavy atoms were examined for suitability for use in the external heavy atom effect for routine phosphorimetry. In previous work only iodine-containing solvent systems have been used, and the incongruity of enhancement results for structurally similar compounds suggests that the ultraviolet transmission characteristics of the solvent systems may be responsible for fractional enhancements. In this study the effect of chlorine-, bromine-, and iodine-containing solvent systems on phosphorescence and fluorescence intensities was investigated. Generally, chlorine-, and bromine-containing solvent systems showed a significant improvement in phosphorimetric enhancements with slightly longer lifetimes than in solvent systems containing iodine. As expected from their smaller spin-orbit coupling, chlorine-containing solvent systems yield smaller enhancements than bromine-containing solvent systems. Solvent systems containing bromine seem to offer the best compromise between ultraviolet transmission characteristics and large spin-orbit coupling constants.     

Determination of Specific Refractive Index Increment （dn/dc）_μ at a Constant Chemical Potential,for Solutions of Polymer in Mixed Solvents by the GPC Method

A new chromatographic method is described for the determination of specific refractive index increment(dn/dc)μ at a constant chemical potential,for polymer/mixed solvent systems.In this method the(dn/dc)is obtained by measuring the areas of solvated-polymer peaks when the mixed solvent is used as an eluent.Values of(dn/dc)μ for the poly(dimethylsiloxane)(PDMS)-benzene-methanol system,determined by the proposed method are in good agreement with those determined by the conventional dialysis method.The new approach has the advantages of simplicity,fast speed,and high reproducibility.The experimental results for stearic acid-chloroform-methanol system show that this method can also be applied to nonpolymer/mixed solvent systems for the determination of(dn/dc)μ.     

A new method to test the effectiveness of sunscreen ingredients in a novel nano-surface skin cell mimic

Photophysical properties of sunscreens are commonly studied in solvent media, which do not mimic the skin, or in complex artificial skin systems, which are difficult to handle. In an earlier study, we showed that polystyrene nanosphere suspensions mimic the mixed polarity environment of skin cell systems. This paper presents a new method to quantify the effectiveness of sunscreens in the polystyrene nanosphere environment. This method utilizes the intrinsic UV-B fluorescence of polystyrene nanospheres. We studied three UV-B sunscreens by this new method and compared their extinction coefficients with observed values in solvent. The values follow the trend observed in solvents, but the ratio of their extinction coefficient in solvent to the value obtained by this new method is 1.3-1.8 instead of 1. This difference might be caused by the mixed polarity or the microgeometry of the nanosphere system. Regardless of the difference in the extinction coefficients, this new system can be used to test hundreds of chemicals for their sunscreening potential in a cost-effective way. One marked advantage of this new method is its ability to test both hydrophobic and hydrophilic sunscreening chemicals in the same environment. This is virtually impossible for current solvent-based models, which require different solvents for hydrophobic and hydrophilic chemicals. The new method also allows the simultaneous evaluation of a host of photophysical properties of sunscreening chemicals.     

The generally useful estimate of solvent systems method facilitates off-line two-dimensional countercurrent chromatography for isolating compositions from Siraitia grosvenorii roots

Solvent system selection is a crucial and the most time-consuming step for successful countercurrent chromatography separation. A thin-layer chromatography-based generally useful estimate of solvent systems method has been developed to simplify the solvent system selection. We herein utilized the method to select a solvent system for off-line two-dimensional countercurrent chromatography to separate chemical compositions from a complex fraction of the Siraitia grosvenorii root extract. The first-dimensional countercurrent separation using chloroform/methanol/water (10:5.5:4.5, v/v/v) yielded four compounds with high purity and three mixture fractions (Fr I, III, and VII). The second-dimensional countercurrent separation conducted on Fr I, III, and VII using the hexane/ethyl acetate/methanol/water (4:6:6:4, 3:7:3:7, v/v/v) and chloroform/methanol/water (10:9:6, v/v/v) solvent systems, respectively, produced another four compounds. Four triterpenoids and four lignans were finally isolated, including two novel compounds. Hence, the generally useful estimate of solvent systems method is a feasible and efficient approach for selecting an applicable solvent system for separating complex samples. In addition, the off-line two-dimensional countercurrent chromatography method can improve both the peak resolution and the capacity of countercurrent chromatography.     

Solubility of pyrene in simple and mixed solvent systems

The solubility of pyrene was experimentally determined in simple and complex solvent systems (single, binary, ternary, quaternary and pentinary solvent systems) composed of benzene, ethylbenzene, hexane, hexanol and methylcyclohexane over a temperature range from 293 to 318 K. In addition, six models were used in this study to represent pyrene solubility in the different solvent systems. The interaction parameters for modified Wilson, NIBS/Redlich-Kister, UNIQUAC and NRTL models were estimated using the solubility data generated for pyrene in single, binary and ternary solvent systems. By re-adjusting the interaction parameters reported for Dortmund UNIFAC and ASOG models, a better representation of the solubility of pyrene was obtained compared to using reported values. Furthermore, a correction term is introduced for the ASOG model in this study to better improve pyrene solubility prediction in simple and mixed solvent systems. These estimated or re-adjusted interaction parameters for the different models, along with the reported parameters for Dortmund UNIFAC and ASOG models, were tested on complex solvent systems (quaternary and pentinary solvent mixtures), in order to check their validity and accuracy for such predictions.     

用改进的重叠分辨率优化法于薄层色谱分离二茂铪化合物

在薄层色谱中分离一系列二茂铪化合物，首先利用黄金分割优选法优化二元展开剂体系，然后按优化结果把二元展开剂混合成四元溶剂体系，共用重叠分辨率法确定四元展开剂体系的最佳组成，分离结果令人满意，同时，本文还对等溶剂强度条件和不等溶剂强度条件下的优化结果做了比较和讨论。     

Aqueous two‐phase systems based on deep eutectic solvents and their application in green separation processes

As a new environmentally friendly separation technology, deep eutectic solvent based aqueous two‐phase systems are extensively applied in various fields. Herein, we review recent advances in this field and highlight the possible directions of future developments. This article focuses on the effects of deep eutectic solvent and inorganic salts on the phase equilibrium, the microstructure of deep eutectic solvent based aqueous two‐phase systems, the applications of deep eutectic solvent based aqueous two‐phase systems in separation (proteins, biopolymers, saponins, and organic acids), and removal and recovery technologies for deep eutectic solvent from aqueous two‐phase systems.