Adsorption of Water-Acetonitrile Mixtures to Model Silica Surfaces
Adsorption of Water-Acetonitrile Mixtures to Model Silica Surfaces
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DOI：
10.1021/jp312501b
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发表时间：
2013-03
影响因子：
3.7
通讯作者：
S. Melnikov;A. Höltzel;A. Seidel-Morgenstern;U. Tallarek
中科院分区：
文献类型：
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作者：
S. Melnikov;A. Höltzel;A. Seidel-Morgenstern;U. Tallarek
亲水相互作用色谱的保留机制依赖于分析物从大部分有机水-乙腈（W/ACN）移动的相分配到固定相的扩展富W层。富W层的形成是由固定相的表面亲水性驱动的。我们研究的起源裸硅胶固定相的亲水性的分子动力学模拟的吸附W/ACN混合物从99/1至2/98（v/v）在三个表面，每个模型一种类型的表面官能团：单硅烷醇基团，偕硅烷醇基团，和硅氧烷桥。由表面W氢键引发，两个硅醇表面积累了致密的W层，它们的W表面过量吸附等温线在整个W/ACN范围内保持正值。硅氧烷桥表面坐标与一个非常紧密的层交替的W和ACN簇; W/ACN混合表面层是反映在S形的吸附等温线与W表面过量低于5…
The retention mechanism of hydrophilic interaction chromatography relies on analyte partitioning from a mostly organic water–acetonitrile (W/ACN) mobile phase into an extended W-rich layer at the stationary phase. The formation of the W-rich layer is driven by the surface hydrophilicity of the stationary phase. We study the origin of the hydrophilicity of bare-silica stationary phases by molecular dynamics simulations of the adsorption of W/ACN mixtures from 99/1 to 2/98 (v/v) at three surfaces that each model one type of surface functional group: single silanol groups, geminal silanol groups, and siloxane bridges. Initiated by surface–W hydrogen bonding, the two silanol surfaces accumulate a dense W layer; their W surface excess adsorption isotherms remain positive over the whole W/ACN range. The siloxane bridges surface coordinates with an exceptionally tight layer of alternate W and ACN clusters; the mixed W/ACN surface layer is reflected in an S-shaped adsorption isotherm with W surface excess below 5...