ETH Zurich, Institute of Process Engineering, Sonneggstrasse 3, CH-8092 Zurich, Switzerland.
J Chromatogr A. 2010 Mar 26;1217(13):2002-12. doi: 10.1016/j.chroma.2010.01.059. Epub 2010 Jan 28.
We report about a new type of composition front in nonlinear chromatography that is called delta-shock, which has to be added to the family of classical transitions, i.e. simple waves, shocks and semi-shocks. Recently, the occurrence of delta-shocks in the case of mixed competitive-cooperative isotherms of the following type n(i) = H(i)c(i)/(1 - K1c1 + K2c2) (i = 1, 2), (with H2 > H1, where components 1 and 2 have anti-Langmuir and Langmuir adsorption behavior, respectively) was predicted theoretically and their behavior was analyzed in the frame of the equilibrium theory of chromatography. The delta-shock can be viewed as a growing traveling spike superimposed to the discontinuity separating the initial and the feed state, which propagates along the column at constant speed and constant rate of growth. In this work we complement these findings from an experimental point of view. The binary system consisting of phenetole (component 1) and 4-tert-butylphenol (component 2) in methanol-water (about 2:1, v/v) on a Zorbax 300StableBond-C18 column from Agilent has been shown, through a series of overloaded pulse experiments and of frontal analysis experiments with the pure compounds, to be subject to the competitive-cooperative isotherm of the type above, up to rather large concentrations. This system does exhibit a delta-shock when the operating conditions are chosen according to theory, namely when phenetole initially saturating the column is displaced by 4-tert-butylphenol, both at high concentrations (the minimum concentrations exhibiting a fully developed delta-shock in this series of experiments were c1 = 20 g/L and c2 = 75 g/L). The propagation of the delta-shock matches the theoretical predictions in terms of both the effect of concentration and the effect of column length. This is the first experimental observation ever of a delta-shock in chromatography. It is noteworthy that the proof of the occurrence of the delta-shock reported here has been obtained in both laboratories cooperating in this project.
我们报告了一种新的非线性色谱组成前沿，称为δ激波，它必须添加到经典跃迁的家族中，即简单波、激波和半激波。最近，在以下类型的混合竞争合作等温线的情况下，预测到了δ激波的发生 n(i) = H(i)c(i)/(1 - K1c1 + K2c2) (i = 1, 2)（其中 H2 > H1，其中组件 1 和 2 分别具有反朗缪尔和朗缪尔吸附行为），并在色谱平衡理论框架内分析了它们的行为。δ激波可以看作是叠加在分离初始状态和进料状态的不连续处的生长传播尖峰，它以恒定速度和恒定增长率沿柱传播。在这项工作中，我们从实验的角度补充了这些发现。由苯醚（组分 1）和 4-叔丁基苯酚（组分 2）在甲醇-水（约 2:1，v/v）中的二元体系在 Agilent 的 Zorbax 300StableBond-C18 柱上已经表明，通过一系列过载脉冲实验和纯化合物的前沿分析实验，该体系符合上述竞争合作等温线类型，直到相当大的浓度。当根据理论选择操作条件时，即当最初使柱饱和的苯醚被高浓度（本系列实验中出现完全发展的δ激波的最小浓度分别为 c1 = 20 g/L 和 c2 = 75 g/L）的 4-叔丁基苯酚取代时，该体系确实会出现δ激波。δ激波的传播在浓度和柱长的影响方面都与理论预测相符。这是色谱中首次观察到δ激波。值得注意的是，这里报告的δ激波的发生证明是在合作进行这个项目的两个实验室中获得的。
