薄层色谱展开机理的探讨

It is found by experiment that the mobile phase at the front of plate moves faster than that at the back ofplate at the same moment.So,a new explanation can be put forward as follows:Upon the thin layer plate sur-face,tliere is an attachment layer of mobiie phase,formed due to wetting force and surface tension。The at-tachment layer is not equithickness everywhere, but the aheader,the thiner.     

吲哚衍生物的薄层色谱分离方法

N-烷基化取代吲哚是吲哚苯酞类压敏染料的重要中间体,通过非N-烷基化取代吲哚进行相转移催化合成。为了采用薄层色谱法跟踪相转移催化反应,必须寻找取代吲哚在N-烷基化前后两者薄层色谱分离的条件。文献较多地报道了吲哚母体及含羧基、羟基、氨基、氰基、酯基等极性吲哚衍生物在有关展开剂中的比移值R_f,而对极性相差很小的N-烷基化和非N-烷基化取代吲哚的分离条件,尚未见详细报道。     

计算机辅助一清片径向展开薄层色谱定性与定量方法初探

径向薄层色谱法（RTLC）是一种将样品呈圆形或环状点样,然后将展开剂从中心向外沿径向输送的薄层色谱方法。在一定的展开距离内,RTLC是一种分离快速、扩散小、不拖尾的高效分离和半制备方法。目前关于RTLC分离的报道较多,但对RTLC定性和定量的报道较少。该文采用自编程方式结合图像处理软件,实现RTLC图像数字化处理,形成RTLC数字化图谱,并对RTLC进行定性与定量方法学验证,建立了一清片RTLC定性与定量方法。辅助计算机技术,对一清片径向展开薄层色谱定性与定量方法进行初探。结果表明,该方法用于RTLC定性的可靠度较好,但用于RTLC的定量,仍有不足之处,这可能与实验环境条件等有关。通过搭载更好的分离和数据采集设备,RTLC会有适合的用武之地。计算机图像处理和自编程方法的结合给了RTLC和其他一些分析相关的技术广阔的发展前景。相信未来在计算机技术的辅助下,薄层色谱技术会迈上一个新的台阶。     

准圆周薄层色谱上行展开的研究

圆周薄层色谱能将样品展开为很细的谱线,具有较高的分辨能力,常用于分析一些难分离的物质。这种色谱方法过去只能采用水平展开方法。我们将普通薄层板修饰成特定形状,用最常见的上行展开法获得近似于圆周薄层的色谱。方法不需要特殊展开装置,应用于皂苷、生物碱的分离鉴定取得很好效果。     

木质素分散剂的薄层色谱

使用薄层色谱可将商品木质素分散剂按分子量大小分离成数个清晰的组分，并证实了展开剂为正醇：异丁醇：水＝８：１０：８．５时，７０℃下活化的硅胶板分离效果最佳。该法不仅可用于实验室内分离木质素，还可作为工业生产的一种检测手段。     

薄层色谱综合分离程度的定量量度

薄层色谱对多元组分的分离程度,目前常用信息量~[1]来度量.但由于计算信息量时需人为地固定R_f值的分段,且认为同一区段内的R_f值等同,而不考虑每相邻两组分的R_f差值,也忽略了同一R_f区段内不同R_f值的细微差异.同时,由于薄层色谱分离的信息量并非连续函数,它只能取很有限的若干个分立值.因此,导致有时相同的信息量值却对应着相去甚远     

径向展开薄层色谱法分离生物碱及其分离效能

径向展开薄层色谱法是一种将样品由中心沿径向向外展开的简便、快速、高效的色谱方法。该文组装了简单的径向展开薄层色谱装置,并建立了朱砂安神丸的径向展开薄层色谱检测法,对其中的生物碱成分进行分离,研究了径向展开薄层色谱的分离特性。从薄层色谱基础理论出发,对径向展开薄层色谱和一般薄层色谱的分离效能进行了比对研究,设计试验进行计算和求解。证明了径向展开薄层色谱法更快、更高效、更经济,适用于生物碱等高极性样品分离。探索了径向展开薄层色谱法高分离效率的理论根源,这一研究思路也为理论创新提供了新的方法和思路。     

薄层色谱实验的改进及教学探讨

以对二甲氨基偶氮苯和反式偶氮苯的混合物作测试样,在薄层板上点样后于单一溶剂和不同比例的混合溶剂中展开,考察样品极性和溶剂极性变化对薄层色谱分离效果的影响;以乙酰苯胺和苯甲酰胺作测试样,点样展开后分别在紫外灯下和碘缸中显色,让学生能够熟练掌握一些常用的薄层色谱显色方法;对实验过程中的一些关键性问题,如物质极性与展开剂的选择、显色方法和分离效果等进行了教学方法探讨。     

薄层色谱溶剂系统优化方法进展

介绍了薄层色谱溶剂分类和溶剂强度参数的进展,综述了近年来优化溶剂系统的九种方法,并对它们进行了比较。     

量气法的改进及应用

通过在反应管(瓶)上端加一恒压分液漏斗以改进一般量气法中隔离反应物的方式称为改进量气法.应用改进量气法对Mg摩尔质量、Al合金中Al含量、无水Na2CO3基准物和工业纯碱总碱度以及钙片中CaCO3含量进行了测定,并将其测定结果与其他测定方法的实验结果进行了比较.结果表明,改进量气法能更方便、简单、快速、环保地应用于有定量气体产生的有关常数测定以及一些定量分析的实验中.     

薄层色谱自动点样仪的研制

介绍了一种由单片机系统控制的薄层色谱自动点样装置,其中喷嘴和机械部分的制作比较实用。采用本文设计,能制出足以与商品仪器媲美的产品,且成本极低。     

Some aspects of TLC in homogenous magnetic fields

This article consists of two parts. First part is a short review about the role of magnetic phenomena in natural environment, human surroundings, and his activities such as science, engineering, and medicine. The second part of the article presents a set of experiments, their results, and data obtained in a static homogenous magnetic field, generated by a pair of permanent magnets and outside it. Adsorption chromatographic systems were investigated: as chromatographed substances – polyaromatic hydrocarbon (PAH), as stationary phase – silica gel 60, as monocomponent mobile phases – n‐hexane, n‐heptane, n‐octane, and benzene were used and binary mobile phases n‐hydrocarbons – benzene. Magnetic field influences retention and efficiency of investigated chromatographic systems. Experimental data analysis (R_F, N) allows us to propose some explanations of the differences between experiment results performed in induced magnetic field and outside it, and in consequence on the changes in the interfacial phenomena induced by field presence.     

香豆素衍生物在数种薄层基质上的室温磷光发射特性

考查了二十多种香豆素衍生物在国产ＭＮ－Ｐ型和ＭＮ－Ｃ型微晶纤维素膜，ＤＥＡＥ离子交换膜上的室温磷光发射特性，并与用滤纸作基质时的结果作了比较。在这些基质上，多数衍生物都能发射不同强度的ＲＴＰ信号，且在其ＲＴＰ特性间呈现，某些取代基效应。从发光稳定性和信背比考虑，ＭＮ－Ｃ型比ＭＮ－Ｐ型膜更适合于这些衍生物的ＲＴＰ发射。     

Current Trends in the Improvement and Development of Catalyst Preparation Methods

The state of the art in the scientific foundations of catalyst preparation is analyzed. New lines and trends in the development of conventional catalyst preparation methods that have appeared in the last 10–15 years are discussed. The theoretical and experimental foundations of the syntheses of porous materials by the sol-gel processing of alkoxides are considered. The synthesis of fine MgO aerogel, which is a unique destructive sorbent and catalyst, is described as one of the numerous examples of the use of this method in combination with supercritical drying. The synthesis of complex oxide and supported metallic catalysts by the sol-gel method is analyzed. Some new approaches to active catalyst deposition are considered, including the deposition-precipitation method. Unconventional methods of catalyst preparation are classified. Tasks are formulated for the development of the scientific basis of these methods.     

基于学生认识发展的教学改进*——以“电离平衡的影响因素”为例

在化学平衡教学后,通过测试和评价学生在“化学平衡”核心主题内容中的认识发展情况,确定下一阶段教学的关键点和发展点,选取电离平衡影响因素为教学载体,设计和实施促进学生认识发展的教学,通过学生测查数据说明基于学生认识发展情况进行教学改进是提高教学效率的有效手段。     

某些分子光谱分析法测定蛋白质的进展

评述包括吸光光度法、荧光光度法及新近发展起来的共振光散射法等分子光谱分析方法定量测定蛋白质的某些进展。表列了重要的反应体系及分析特征。引用文献97种。     

A new reagent for the visualisation of N-alkylureas on TLC plates

Summary A new reagent for the visualisation of substituted ureas on TLC plates byin situ nitrosation is described. The procedure involves spraying the plates with two different reagents, and takes about five minutes. The method was tested on four different substituted ureas. A positive identification of nitroso compounds made byin situ nitrosation is discussed.     

Some Optional Methods of Activation Energy Determination on Pyrolysis

Kinetics and Catalysis - In this paper, we investigated two possible directions that help to provide new methods of determining activation energy in kinetic analysis during corn stover pyrolysis....     

Development and Validation of HPLC,TLC and Derivative Spectrophotometric Methods for the Analysis of Ezetimibe in the Presence of Alkaline Induced Degradation Products

Reversed phase‐high performance liquid chromatography (RP‐HPLC), thin layer chromatography (TLC) densitometry and first derivative spectrophotometry (1D) techniques are developed and validated as a stability‐indicating assay of ezetimibe in the presence of alkaline induced degradation products. RP‐HPLC method involves an isocratic elution on a Phenomenex Luna 5μ C₁₈ column using acetonitrile: water: glacial acetic acid (50:50:0.1 v/v/v) as a mobile phase at a flow rate of 1.5 mL/min. and a UV detector at 235 nm. TLC densitometric method is based on the difference in Rf‐values between the intact drug and its degradation products on aluminum‐packed silica gel 60 F₂₅₄ TLC plates as stationary phase with isopropanol: ammonia 33% (9:1 v/v) as a developing mobile phase. On the fluorescent plates, the spots were located by fluorescence quenching and the densitometric analysis was carried out at 250 nm. Derivative spectrophotometry, the zero‐crossing method, ezetimibe was determined using first derivative at 261 nm in the presence of its degradation products. Calibration graphs of the three suggested methods are linear in the concentration ranges 1–10 mcg/mL, 0.1–1 mg/mL and 1–16 mcg/mL with a mean percentage accuracy of 99.05 ± 0.54%, 99.46 ± 0.63% and 99.24 ± 0.82% of bulk powder, respectively. The three proposed methods were successfully applied for the determination of ezetimibe in raw material and pharmaceutical dosage form; the results were statistically analyzed and compared with those obtained by the reported method. Validation parameters were determined for linearity, accuracy and precision; selectivity and robustness and were assessed by applying the standard addition technique.