共查询到20条相似文献,搜索用时 171 毫秒
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色谱流出曲线方程的讨论周申范(南京理工大学化工学院210094)1引言由塔板理论导出的色谱流出曲线方程式是色谱理论的基础。它以简单而优雅的形式指出了有关一个柱内色谱峰分离的定性和定量机理。尽管它有某些不足,但由于它能很好地解释流出曲线的形状、浓度极大... 相似文献
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直接从原始塔板理论的级数形式色谱流出曲线表达式出发,得到了流出曲线一级原点矩及二、三级中心矩的数学表达式,并依此讨论了色谱峰的形状特征及各种因素对峰形的影响规律。本文结果直接证实原始塔板理论曲线为不对称分布,描述峰型不对称性的偏态系数与塔片数及容量因子有关,且随容量因子的增大逐渐变小。当塔片数很大时,容量因子不很小的组分流出曲线有相似的对称性。 相似文献
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色谱柱分离过程驰豫理论:流出曲弛的动力学本质 总被引:2,自引:0,他引:2
在分析型线性色谱中,流出曲线一般表现为拖尾的形式,这种现象可以采用多种机理加以解释。模仿动力学驰豫理论的假设条件,认为溶质在柱过程中的迁移以跃迁形式完成,得到了浓度分布曲线的数学表达式。 相似文献
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定量描述气相色谱柱效的方法,一般采用Martin和Synge引进的理论塔板概念。有时也采用Purnell引进的有效塔板概念。为使理论塔板和有效塔板统一起来,并使新的柱效与容量比(K)无关,本文根据Jan Ceulemans的工作,介绍一种新的气相色谱柱效测量方法 相似文献
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The chromatographic behaviour of 48 alkaloids has been studied on Bio-Rad AG 1-X4, Cellex D and microcrystalline cellulose, eluting with solutions of different pH but constant ionic strength (0.5). Many interesting separations were effected on both AG 1-X4 and Cellex D layers. The influence of pH on the chromatographic behaviour of alkaloids has been quantitatively studied and an equation was used that expresses the behaviour of the alkaloids on both AG 1-X4 (AcO-) and microcrystalling cellulose layers. The nonapplicability of this equation to Cellex D layers is discussed. 相似文献
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Toumi A Engell S Ludemann-Hombourger O Nicoud RM Bailly M 《Journal of chromatography. A》2003,1006(1-2):15-31
A new continuous chromatographic process (Varicol) has been presented recently. Its basic principle consists, in contrast to the traditional simulated moving bed (SMB) technology, of an asynchronous shift of the inlet/outlet lines in a multi-column system with a recycle loop. Due to the stronger influence of the discrete dynamics on the plant behavior, the design of a Varicol process requires the use of model-based optimization to take advantage of the very high flexibility of this process. The equilibrium theory which has been successfully applied to SMB by many practitioners fails to predict the region of complete separation accurately. In this paper, we present a rigorous model-based optimization framework, which can handle the SMB and the novel Varicol process in a systematic manner. The feasibility of the approach is demonstrated by the separation of a mixture of propranolol isomers which exhibits a highly non-linear multi-component adsorption behavior. Experimental results are presented and discussed. 相似文献
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本文提出用显色剂--对-乙酰基偶氮胂作淋洗剂,阳离子交换分离钍与稀土(铀、钪),流出液可直接用光度法测定,将分离和测定结合起来的新方法.操作较简便快速.分离测定了矿石中稀土及钍,结果尚属满意. 相似文献
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The evaluation and prediction of the shape of asymmetric gas chromatographic peaks is important as the knowledge of the amount of tailing permits to foresee the resolution between closely eluting peaks and to select the best analytical conditions for an efficient and rapid separation. A model function was tested in order to approximate the true peak shape obtained on non-polar column by injecting different compounds. The trend of the parameters involved in the used equation has been investigated as a function of column temperature and inlet pressure. The reproduction of the symmetrical or asymmetrical shape of gas chromatographic peaks is satisfactory and the method also permits to predict the shape of peaks obtained in different conditions of temperature and pressure. 相似文献
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色谱法分离硒和碲,多以强酸为洗脱液[1,2],有关高效离子交换色谱法(HPIEC)分离硒、碲的工作,似尚未见报导。本文用HPIEC法在十分钟内分离并测定了硒和碲。 相似文献
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The retention behavior of components analyzed by chromatography varies with instrumental settings. Being able to predict how changes in these settings alter the elution pattern is useful, both with regards to component identification, as well as with regards to optimization of the chromatographic system. In this work, it is shown how experimental designs can be used for this purpose. Different experimental designs for response surface modeling of the separation of fatty acid methyl esters (FAME) as function of chromatographic conditions in GC have been evaluated. Full factorial, central composite, Doehlert and Box-Behnken designs were applied. A mixture of 38 FAMEs was separated on a polar cyanopropyl substituted polysilphenylene-siloxane phase capillary column. The temperature gradient, the start temperature of the gradient, and the carrier gas velocity were varied in the experiments. The modeled responses, as functions of chromatographic conditions, were retention time, retention indices, peak widths, separation efficiency and resolution between selected peak pairs. The designs that allowed inclusion of quadratic terms among the predictors performed significantly better than factorial design. Box-Behnken design provided the best results for prediction of retention, but the differences between the central composite, Doehlert and Box-Behnken designs were small. Retention indices could be modeled with much better accuracy than retention times. However, because the errors of predicted tR of closely eluting peaks were highly correlated, models of resolution (Rs) that were based on retention time had errors in the same range as corresponding models based on ECL. 相似文献
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甲壳素色谱柱富集—快速吸光光度法测定环境试样中痕量铁 总被引:1,自引:0,他引:1
研究了甲壳素色谱柱富集Fe(Ⅱ)-磺基水杨酸-十八烷基二甲基氨基乙酸的红紫色缔合物,用磺基水杨酸洗脱后,在分光光度计上直接测定洗脱液的吸光度,方法快速,简单、富集倍数高,用于环境水样中痕量铁的测定,结果令人满意。 相似文献
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Multiple hyphenation of liquid chromatography with nuclear magnetic resonance spectroscopy, mass spectrometry and beyond 总被引:1,自引:0,他引:1
Wilson ID 《Journal of chromatography. A》2000,892(1-2):315-327
The advent of sensitive and reliable HPLC-NMR and HPLC-MS systems has revolutionised the identification of compounds eluting from chromatographic systems. More recently systems have been described wherein both NMR and MS are used together to provide an immensely powerful means of characterising compounds in chromatographic eluents. Here the construction and application of combined HPLC-NMR-MS systems to the analysis of mixtures of pharmaceuticals, drug metabolites in biological fluids and natural products in plant extracts is reviewed. In addition preliminary work with alternative systems such as HPLC-UV-NMR-FTIR-MS is highlighted and the prospects for such complex systems considered. 相似文献
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A new method for determination of volatile terpenoids in wine is proposed. An off-line solid phase extraction—gas chromatographic method has been used for the determination. The influence of several extraction variables was studied, including the solid phase employed (C-18 versus divinylbenzene-based), eluting solvent (n-pentane, dichloromethane, ethanol and methanol), volume of eluting solvent (1-4 ml) and drying time (0-20 min). Complete recovery of volatile terpenoids from several kinds of wines was obtained under the optimized conditions. 相似文献
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pH gradient high-performance liquid chromatography (HPLC) is a method of reversed-phase high-performance liquid chromatography suitable for ionogenic substances. It consists in programmed increase during the chromatographic process of the eluting strength of eluent with respect to the analytes separated. On the analogy of the conventional organic modifier gradient reversed-phase HPLC, in the pH gradient approach the eluting strength of the mobile phase increases due to its changing pH: increasing in case of acids or decreasing in case of bases. At the same time the content of organic modifier remains constant. A theory of the pH gradient HPLC has been elaborated. The resulting mathematical model is easily manageable. Its ability to predict changes in retention and separation of analytes following the changes in chromatographic conditions is demonstrated. The pH gradient method is uniquely suitable to determine pKa values of analytes. An equation is presented allowing to calculate pKa values basing on appropriate retention data. The effects on pKa are discussed of the concentration of methanol in the mobile phase. The RP HPLC-derived pKa data correlate to the reference pKa values (w(w)pKa) but are not identical. That may be explained by the effects on the chromatographically determined pKa of the specific interactions of analytes with stationary phases. The proposed pH gradient RP HPLC procedure offers a fast and convenient means to get comparable acidity parameters for larger series of compounds, like drug candidates, also when the analytes are available only in minute amounts and/or as complex mixtures. 相似文献