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Axial heterogeneities in capillary ultrahigh pressure liquid chromatography columns: Chromatographic and bed morphological characterization
Journal of Chromatography A ( IF 4.1 ) Pub Date : 2018-07-07 , DOI: 10.1016/j.chroma.2018.07.037
Arved E. Reising , Justin M. Godinho , Janek Bernzen , James W. Jorgenson , Ulrich Tallarek

We study axial heterogeneities in capillary ultrahigh pressure liquid chromatography (UHPLC) columns through kinetic performance and bed morphological analysis. Two columns are used in this work, a 75 μm i.d. × 100 cm column packed with 1.3 μm C18-silica particles and a 75 μm i.d. × 45 cm column packed with 1.9 μm C18-silica particles. The long column is chromatographically characterized and is afterwards sectioned into three segments, each analyzed individually. The column packed with the 1.9 μm particles is subjected to a bed morphological analysis using confocal laser scanning microscopy near the inlet, center, and outlet of the column. Chromatographic and morphological characterizations reveal highest separation efficiency and most homogeneous bed microstructure towards the column outlet. Kinetic performance data for inlet and central packing segments indicate enhanced contributions from wall effects to a transcolumn flow heterogeneity. Bed morphological data reveal systematic changes in geometrical and frictional wall effects along the bed: from inlet to outlet, bed morphologies increasingly reflect packing microstructures associated with concentrated slurries. Variations in separation efficiency and bed morphology can be related to the constant-pressure packing mode; the decrease in packing rate along the bed leaves fewer chances for particle rearrangement and bed consolidation from inlet to outlet. It explains the relatively uniform bed morphology towards the outlet and also the relatively loose wall region near the inlet. Bed microstructural features are discussed in a context of previous observations made in the characterization of capillary UHPLC columns.



中文翻译:

毛细管超高压液相色谱柱中的轴向异质性:色谱和床层形态表征

我们通过动力学性能和床形态分析研究毛细管超高压液相色谱(UHPLC)色谱柱中的轴向异质性。在这项工作中使用了两根色谱柱:填充有1.3μmC18二氧化硅颗粒的75μmid×100 cm色谱柱和填充有1.9μmC18二氧化硅颗粒的75μmid×45 cm色谱柱。对长柱进行色谱分析,然后将其分成三部分,分别进行分析。使用共聚焦激光扫描显微镜在装有色谱柱的入口,中心和出口附近对装有1.9μm颗粒的色谱柱进行床层形态分析。色谱和形态学表征显示出最高的分离效率和朝向色谱柱出口的最均匀的床微观结构。入口和中央填料段的动力学性能数据表明,壁效应对跨柱流动异质性的贡献增加。床层形态数据揭示了沿床层几何和摩擦壁效应的系统变化:从入口到出口,床层形态越来越多地反映了与浓浆有关的填料微观结构。分离效率和床形态的变化可能与恒压填充方式有关。沿床的装填速率的降低为从入口到出口的颗粒重排和床固结的机会减少了。它解释了朝向出口的相对均匀的床层形态以及入口附近的相对较松的壁区域。

更新日期:2018-07-07
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