Gritti Fabrice, Guiochon Georges
Department of Chemistry, University of Tennessee, Knoxville, TN 37996-1600, USA.
J Chromatogr A. 2004 Feb 27;1028(1):105-19. doi: 10.1016/j.chroma.2003.11.089.
Single-component adsorption isotherm data were acquired by frontal analysis (FA) for phenol and caffeine on a new C18-Chromolith column (Merck, Darmstadt, Germany), using a water-rich mobile phase (methanol/water, 15/85, v/v). These data were modeled for best agreement between the experimental data points and the adsorption isotherm model. The adsorption-energy distributions, based on the expectation-maximization (EM) procedure, were also derived and used for the selection of the best isotherm model. The adsorption energy distributions (AEDs) for phenol and caffeine converged toward a trimodal and a quadrimodal distribution, respectively. Energy distributions with more than two modes had not been reported before for the adsorption of these compounds on packed columns. The third high energy mode observed for both phenol and caffeine seems to be specific of the surface of the monolithic column while the first and second low energy modes have the same physical origin as the two modes detected on packed columns. These results suggest significant differences between the structures of the porous silica in these different materials.
采用前沿分析法（FA），以富含水的流动相（甲醇/水，15/85，v/v），在新型C18 - 整体柱（德国默克公司，达姆施塔特）上获取了苯酚和咖啡因的单组分吸附等温线数据。对这些数据进行建模，以使实验数据点与吸附等温线模型达到最佳拟合。基于期望最大化（EM）程序，还推导了吸附能分布，并用于选择最佳等温线模型。苯酚和咖啡因的吸附能分布（AEDs）分别趋向于三峰分布和四峰分布。对于这些化合物在填充柱上的吸附，此前尚未报道过具有两个以上模式的能量分布。苯酚和咖啡因均观察到的第三个高能模式似乎是整体柱表面所特有的，而第一和第二个低能模式与在填充柱上检测到的两个模式具有相同的物理起源。这些结果表明，这些不同材料中多孔二氧化硅的结构存在显著差异。
